ASP.NET cannot get rid of “500- Internal server error”

I am creating an ASP.NET webage that retrieve and insert data inside CRM 2011.
Everything was going fine, the page was being deployed to the server and it was ready to test.

Suddenly a new change come out, and after I deleted the files in the server and republished the project (I know it is not needed, but still..) I could not access the website anymore.

All I get is 500- Internal server error
There is a problem with the resource you are looking for, and it cannot be displayed.

I tried turning on the debug function with debug="True" on the page header, I set

<customErrors mode="Off"/>
<compilation debug="true" targetFramework="4.5"/>

On the web.config file, and I also tried adding

<httpErrors errorMode="Detailed" />

but none of them helped having a better error message.

My web.config file is:

   <?xml version="1.0"?>
<!--
  For more information on how to configure your ASP.NET application, please visit
  http://go.microsoft.com/fwlink/?LinkId=169433
  -->
<configuration>
  <configSections>
    <!-- For more information on Entity Framework configuration, visit http://go.microsoft.com/fwlink/?LinkID=237468 -->
    <section name="entityFramework" type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=5.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false"/>
  </configSections>
  <connectionStrings>
    <add name="DefaultConnection" providerName="System.Data.SqlClient" connectionString="Data Source=(LocalDb)\v11.0;Initial Catalog=aspnet-ASP-20130619150943;Integrated Security=SSPI;AttachDBFilename=|DataDirectory|\aspnet-ASP-20130619150943.mdf"/>
  </connectionStrings>
  <!--
    For a description of web.config changes for .NET 4.5 see http://go.microsoft.com/fwlink/?LinkId=235367.

    The following attributes can be set on the <httpRuntime> tag.
      <system.Web>
        <httpRuntime targetFramework="4.5" />
      </system.Web>
  -->
  <system.web>
    <customErrors mode="Off"/>
    <compilation debug="true" targetFramework="4.5"/>
    <httpRuntime/>
    <pages controlRenderingCompatibilityVersion="4.0">
      <namespaces>
        <add namespace="System.Web.Optimization"/>
      </namespaces>
      <controls>
        <add assembly="Microsoft.AspNet.Web.Optimization.WebForms" namespace="Microsoft.AspNet.Web.Optimization.WebForms" tagPrefix="webopt"/>
      </controls>
    </pages>
    <authentication mode="Forms">
      <forms loginUrl="~/Account/Login" timeout="2880" defaultUrl="~/"/>
    </authentication>
    <profile defaultProvider="DefaultProfileProvider">
      <providers>
        <add name="DefaultProfileProvider" type="System.Web.Providers.DefaultProfileProvider, System.Web.Providers, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" connectionStringName="DefaultConnection" applicationName="/"/>
      </providers>
    </profile>
    <membership defaultProvider="DefaultMembershipProvider">
      <providers>
        <add name="DefaultMembershipProvider" type="System.Web.Providers.DefaultMembershipProvider, System.Web.Providers, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" connectionStringName="DefaultConnection" enablePasswordRetrieval="false" enablePasswordReset="true" requiresQuestionAndAnswer="false" requiresUniqueEmail="false" maxInvalidPasswordAttempts="5" minRequiredPasswordLength="6" minRequiredNonalphanumericCharacters="0" passwordAttemptWindow="10" applicationName="/"/>
      </providers>
    </membership>
    <roleManager defaultProvider="DefaultRoleProvider">
      <providers>
        <add name="DefaultRoleProvider" type="System.Web.Providers.DefaultRoleProvider, System.Web.Providers, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" connectionStringName="DefaultConnection" applicationName="/"/>
      </providers>
    </roleManager>
    <!--
            If you are deploying to a cloud environment that has multiple web server instances,
            you should change session state mode from "InProc" to "Custom". In addition,
            change the connection string named "DefaultConnection" to connect to an instance
            of SQL Server (including SQL Azure and SQL  Compact) instead of to SQL Server Express.
      -->
    <sessionState mode="InProc" customProvider="DefaultSessionProvider">
      <providers>
        <add name="DefaultSessionProvider" type="System.Web.Providers.DefaultSessionStateProvider, System.Web.Providers, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" connectionStringName="DefaultConnection"/>
      </providers>
    </sessionState>
  </system.web>
  <runtime>
    <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
      <dependentAssembly>
        <assemblyIdentity name="DotNetOpenAuth.Core" publicKeyToken="2780ccd10d57b246"/>
        <bindingRedirect oldVersion="1.0.0.0-4.0.0.0" newVersion="4.1.0.0"/>
      </dependentAssembly>
      <dependentAssembly>
        <assemblyIdentity name="DotNetOpenAuth.AspNet" publicKeyToken="2780ccd10d57b246"/>
        <bindingRedirect oldVersion="1.0.0.0-4.0.0.0" newVersion="4.1.0.0"/>
      </dependentAssembly>
    </assemblyBinding>
  </runtime>
  <entityFramework>
    <defaultConnectionFactory type="System.Data.Entity.Infrastructure.SqlConnectionFactory, EntityFramework"/>
  </entityFramework>

  <appSettings>
    <add key="CRMUserName" value="xxxx" />
    <add key="CrmUserPassword" value="yyyy" />
    <add key="OrganizationUri" value="https://uuuuuu/XRMServices/2011/Organization.svc" />
    <add key="HomeRealmUri" value="" />
  </appSettings>
</configuration>

I get an error message when I run the page.
The error message is:
An error occurred when verifying security for the message
System.ServiceModel.FaultException: An error occurred when verifying security for the message.

The section where the error fires is:

  RetrieveAttributeRequest retrieveFreightTerm = new RetrieveAttributeRequest
  {
    EntityLogicalName = "account",
    LogicalName = "address1_freighttermscode",
    RetrieveAsIfPublished = true
  };

Any ideas?