Utilizando String de conexão Web.Config

Fala ai Pessoal, td bem?To precisando de uma ajudinhaTo querendo utilizar string de conexão com o web config + to tendo um erro segue abaixo código q estou utilizandoquando conecto via Sql connection, o codigo ffunciona perfeitasmente, ja quando uso via web config retorna o erro abaixoWEB CONFIG<?xml version="1.0"?><configuration>	<appSettings/>	<connectionStrings> <add name="mitConn" connectionString="server=localhost;uid=sa;pwd=;database=mitsat" providerName="System.Data.SqlClient"/>	</connectionStrings>	<system.web> <compilation debug="true"/>	</system.web></configuration>C#//SqlConnection mitConn = new SqlConnection("server=localhost;uid=sa;pwd=;database=mitsat");String mitConn = ConfigurationSettings.AppSettings("mitConn");mitConn.Open();SqlCommand cmdMit = new SqlCommand("INSERT INTO mit_teste(teste)values('" + empresa + "')", mitConn);cmdMit.ExecuteNonQuery();mitConn.Close();ERROCompilation ErrorDescription: An error occurred during the compilation of a resource required to service this request. Please review the following specific error details and modify your source code appropriately.Compiler Error Message: CS0118: 'System.Configuration.ConfigurationSettings.AppSettings' is a 'property' but is used like a 'method'Source Error:Line 24: string empresa = txtEmpresa.Text;Line 25: //SqlConnection mitConn = new SqlConnection("server=localhost;uid=sa;pwd=;database=mitsat");Line 26: String mitConn = ConfigurationSettings.AppSettings("mitConn");Line 27: mitConn.Open();Line 28: SqlCommand cmdMit = new SqlCommand("INSERT INTO mit_teste(teste)values('" + empresa + "')", mitConn);AGRADEÇO SE ALGUEM PUDER ME AJUDAR A RESOLVER ESSE PROBLEMINHA. OBRIGADO