Não sei o que fazer com esse erro? (jjava.lang.NoClassDefFoundError:)

Pessoal uso o Netbeans 8.0 eu travei em um erro e não consigo progredir.

Já procurei por toda internet e nada.

Erro:

Exception in thread "main" java.lang.NoClassDefFoundError: autenticacao/Logon
at bolaofuleco.BolaoFuleco.main(BolaoFuleco.java:23)
Caused by: java.lang.ClassNotFoundException: autenticacao.Logon
at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
... 1 more
Java Result: 1

Classes:

Principal:

package bolaofuleco;

import autenticacao.Logon;
import javax.swing.JFrame;

/**
*
* @author CaioCezar
*/
public class BolaoFuleco {

/**
* @param args the command line arguments
*/
public static void main(String[] args) {

 Logon login;
 login = new Logon(new JFrame(), true);
 }

}

Classe Logon:

package autenticacao;

import bolaofuleco.Usuario;
import bolaofuleco.bolaoJFrame;
import dao.UsuarioDao;
import javax.swing.JDialog;

public class Logon extends JDialog {

 private Usuario usuario;

 public Logon(java.awt.Frame parent, boolean modal) {
 super(parent,modal);
 initComponents();
 setLocationRelativeTo(null);
 setVisible(true);
 this.usuario=null;

 }

 @SuppressWarnings("unchecked")
 // <editor-fold defaultstate="collapsed" desc="Generated Code">
 private void initComponents() {

 jPanel1 = new javax.swing.JPanel();
 jLabel4 = new javax.swing.JLabel();
 jLabel5 = new javax.swing.JLabel();
 jPanel2 = new javax.swing.JPanel();
 jLabel1 = new javax.swing.JLabel();
 jLabel2 = new javax.swing.JLabel();
 txtSenha = new javax.swing.JPasswordField();
 txtUsuario = new javax.swing.JTextField();
 btLimpar = new javax.swing.JButton();
 jButton2 = new javax.swing.JButton();
 lbInformacao = new javax.swing.JLabel();
 btCadastrar = new javax.swing.JButton();
 jLabel3 = new javax.swing.JLabel();

 setDefaultCloseOperation(javax.swing.WindowConstants.DISPOSE_ON_CLOSE);
 setTitle("Login Bolão 2014");
 setBounds(new java.awt.Rectangle(100, 0, 0, 0));
 setResizable(false);
 addWindowListener(new java.awt.event.WindowAdapter() {
 public void windowClosed(java.awt.event.WindowEvent evt) {
 formWindowClosed(evt);
 }
 });

 jPanel1.setBackground(new java.awt.Color(255, 255, 255));

 jLabel5.setIcon(new javax.swing.ImageIcon(getClass().getResource("/img/Bolão Logotipo_p.png"))); // NOI18N

 jPanel2.setBackground(new java.awt.Color(255, 255, 255));

 jLabel1.setText("Usuário:");

 jLabel2.setText("Senha:");

 txtSenha.setBorder(javax.swing.BorderFactory.createLineBorder(new java.awt.Color(153, 153, 153)));

 txtUsuario.setBorder(javax.swing.BorderFactory.createLineBorder(new java.awt.Color(153, 153, 153)));

 btLimpar.setText("limpar");
 btLimpar.addActionListener(new java.awt.event.ActionListener() {
 public void actionPerformed(java.awt.event.ActionEvent evt) {
 btLimparActionPerformed(evt);
 }
 });

 jButton2.setText("entrar");
 jButton2.addActionListener(new java.awt.event.ActionListener() {
 public void actionPerformed(java.awt.event.ActionEvent evt) {
 jButton2ActionPerformed(evt);
 }
 });

 lbInformacao.setForeground(new java.awt.Color(255, 51, 0));

 btCadastrar.setText("novo por aqui?");
 btCadastrar.setToolTipText("");
 btCadastrar.addActionListener(new java.awt.event.ActionListener() {
 public void actionPerformed(java.awt.event.ActionEvent evt) {
 btCadastrarActionPerformed(evt);
 }
 });

 javax.swing.GroupLayout jPanel2Layout = new javax.swing.GroupLayout(jPanel2);
 jPanel2.setLayout(jPanel2Layout);
 jPanel2Layout.setHorizontalGroup(
 jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
 .addGroup(jPanel2Layout.createSequentialGroup()
 .addContainerGap()
 .addGroup(jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
 .addComponent(lbInformacao, javax.swing.GroupLayout.Alignment.LEADING, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
 .addGroup(jPanel2Layout.createSequentialGroup()
 .addGap(0, 0, Short.MAX_VALUE)
 .addGroup(jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
 .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanel2Layout.createSequentialGroup()
 .addGroup(jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
 .addComponent(jLabel2)
 .addComponent(jLabel1))
 .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
 .addGroup(jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
 .addComponent(txtSenha, javax.swing.GroupLayout.Alignment.TRAILING, javax.swing.GroupLayout.DEFAULT_SIZE, 173, Short.MAX_VALUE)
 .addComponent(txtUsuario, javax.swing.GroupLayout.Alignment.TRAILING)))
 .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
 .addComponent(btCadastrar, javax.swing.GroupLayout.PREFERRED_SIZE, 134, javax.swing.GroupLayout.PREFERRED_SIZE)
 .addGroup(jPanel2Layout.createSequentialGroup()
 .addComponent(btLimpar)
 .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
 .addComponent(jButton2))))))
 .addGap(278, 278, 278))
 );
 jPanel2Layout.setVerticalGroup(
 jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
 .addGroup(jPanel2Layout.createSequentialGroup()
 .addComponent(lbInformacao, javax.swing.GroupLayout.PREFERRED_SIZE, 19, javax.swing.GroupLayout.PREFERRED_SIZE)
 .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
 .addGroup(jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
 .addComponent(txtUsuario, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
 .addComponent(jLabel1))
 .addGap(5, 5, 5)
 .addGroup(jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
 .addComponent(txtSenha, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
 .addComponent(jLabel2))
 .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
 .addGroup(jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
 .addComponent(btLimpar)
 .addComponent(jButton2))
 .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
 .addComponent(btCadastrar)
 .addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
 );

 jLabel3.setIcon(new javax.swing.ImageIcon(getClass().getResource("/img/fundo login.png"))); // NOI18N

 javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1);
 jPanel1.setLayout(jPanel1Layout);
 jPanel1Layout.setHorizontalGroup(
 jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
 .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanel1Layout.createSequentialGroup()
 .addContainerGap()
 .addComponent(jLabel3)
 .addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
 .addGroup(jPanel1Layout.createSequentialGroup()
 .addGap(19, 19, 19)
 .addComponent(jLabel5)
 .addGap(28, 28, 28)
 .addComponent(jPanel2, javax.swing.GroupLayout.PREFERRED_SIZE, 258, javax.swing.GroupLayout.PREFERRED_SIZE)
 .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
 .addComponent(jLabel4))
 );
 jPanel1Layout.setVerticalGroup(
 jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
 .addGroup(jPanel1Layout.createSequentialGroup()
 .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
 .addGroup(jPanel1Layout.createSequentialGroup()
 .addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
 .addComponent(jLabel4)
 .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))
 .addGroup(jPanel1Layout.createSequentialGroup()
 .addContainerGap()
 .addGroup(jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
 .addComponent(jPanel2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
 .addComponent(jLabel5))
 .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)))
 .addComponent(jLabel3))
 );

 javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
 getContentPane().setLayout(layout);
 layout.setHorizontalGroup(
 layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
 .addComponent(jPanel1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
 );
 layout.setVerticalGroup(
 layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
 .addComponent(jPanel1, javax.swing.GroupLayout.Alignment.TRAILING, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
 );

 pack();
 }// </editor-fold>

 public Usuario getUsuario() {
 return usuario;
 }

 private void formWindowClosed(java.awt.event.WindowEvent evt) {
 // TODO add your handling code here:

 }

 private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {
 // TODO add your handling code here:
 UsuarioDao dao = new UsuarioDao();
 Usuario user = dao.validaUsuarioSenha(txtUsuario.getText(), new String (txtSenha.getPassword()));
 if(Usuario != null){
 this.usuario=user;
 dispose();
 }else{
 lbInformacao.setText("Usuário ou senha incorretos");
 txtUsuario.requestFocus(true);
 }

 }

 private void btLimparActionPerformed(java.awt.event.ActionEvent evt) {
 txtUsuario.setText("");
 txtSenha.setText("");
 txtUsuario.requestFocus(true);
 }

 private void btCadastrarActionPerformed(java.awt.event.ActionEvent evt) {
 bolaoJFrame.setNewUser(true);

 dispose();
 }

 /**
 * @param args the command line arguments
 */
 public static void main(String args[]) {
 /* Set the Nimbus look and feel */
 //<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
 /* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
 * For details see [http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html](http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html)
 */
 try {
 for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
 if ("Nimbus".equals(info.getName())) {
 javax.swing.UIManager.setLookAndFeel(info.getClassName());
 break;
 }
 }
 } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | javax.swing.UnsupportedLookAndFeelException ex) {
 java.util.logging.Logger.getLogger(Logon.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
 }
 //</editor-fold>

 /* Create and display the dialog */
 java.awt.EventQueue.invokeLater(new Runnable() {
 @Override
 public void run() {
 Logon dialog = new Logon(new javax.swing.JFrame(), true);
 dialog.addWindowListener(new java.awt.event.WindowAdapter() {
 @Override
 public void windowClosing(java.awt.event.WindowEvent e) {

 }
 });
 dialog.setVisible(true);
 }
 });
 }

 // Variables declaration - do not modify
 private javax.swing.JButton btCadastrar;
 private javax.swing.JButton btLimpar;
 private javax.swing.JButton jButton2;
 private javax.swing.JLabel jLabel1;
 private javax.swing.JLabel jLabel2;
 private javax.swing.JLabel jLabel3;
 private javax.swing.JLabel jLabel4;
 private javax.swing.JLabel jLabel5;
 private javax.swing.JPanel jPanel1;
 private javax.swing.JPanel jPanel2;
 private javax.swing.JLabel lbInformacao;
 private javax.swing.JPasswordField txtSenha;
 private javax.swing.JTextField txtUsuario;
 // End of variables declaration
}

Agradeço a ajuda e se precisarem de mais alguma classe é só pedir.