C# Gridview nao atualiza

Boa tarde pessoal;

Eu tenho uma GridView que lista uma coleção que tem o ShowDeleteButton = True; , Quando clico em delete, deleta, mas nao atuliza a grid.

minha GridView

<asp:GridView ID="gvContato" runat="server" AutoGenerateColumns="False"
CellPadding="4" ForeColor="#333333" GridLines="None" Width="100%" OnRowCommand="gvContato_RowCommand">

 <RowStyle BackColor="#F7F6F3" ForeColor="#333333" />
 <Columns>
 <asp:BoundField DataField="IdTypeContact" HeaderText="Tipo de Contato" HeaderStyle-Width="150px" ItemStyle-Width="150px" HeaderStyle-HorizontalAlign="Left" />
 <asp:BoundField DataField="Valor" HeaderText="Valor do Contato" HeaderStyle-HorizontalAlign="Left" />
 <asp:CommandField DeleteText="delete" ShowDeleteButton="true"/>
 </Columns>
 <FooterStyle BackColor="#5D7B9D" Font-Bold="True" ForeColor="White" />
 <PagerStyle BackColor="#284775" ForeColor="White" HorizontalAlign="Center" />
 <SelectedRowStyle BackColor="#E2DED6" Font-Bold="True" ForeColor="#333333" />
 <HeaderStyle BackColor="#5D7B9D" Font-Bold="True" ForeColor="White" />
 <EditRowStyle BackColor="#999999" />
 <AlternatingRowStyle BackColor="White" ForeColor="#284775" />
 </asp:GridView>

Ação

protected void gvContato_RowCommand(object sender, GridViewCommandEventArgs e)
{

 if (e.CommandName == "Delete")
 {
 ContatoField cfDelete = null;
 List<ContatoField> lDel = (List<ContatoField>)gvContato.DataSource;

 int index = Convert.ToInt32(e.CommandArgument);
 GridViewRow gvr = gvContato.Rows[index];

 foreach (ContatoField cf in lDel)
 {
 if (cf.IdTypeContact == Convert.ToInt32(gvr.Cells[0].Text) &&
 cf.Valor.Trim() == gvr.Cells[1].Text.Trim())
 {
 cfDelete = cf;
 break;
 }

 }

 lDel.Remove(cfDelete);
 gvContato.DataSource = lDel;
 gvContato.DataBind();

 //MostraContato();
 }
 }

Obrigado galera,

me ajudem por favor...