Problem running WCF service on IIS 7.5

Hi,

Maybe someone can help me.

I'm hosting WCF service on IIS. The .svc file is accessible from a browser. It works locally but when I publish on the server and I want to call a method from my client, I always got an HTTP Status 500 from the server.

Here is my web.config file

<?xml version="1.0"?><configuration><system.web><compilation debug="true" targetFramework="4.0" /><!-- Allow receiving of large files, maxRequestLength is in kB --><httpRuntime maxRequestLength="2097151" executionTimeout="300" /></system.web><system.serviceModel><services><service behaviorConfiguration="WebServices.MVSWebServicesBehavior"
        name="WebServices.MVSWebServices"><endpoint address="" binding="basicHttpBinding" contract="WebServices.MVSWebServices_I" /><endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange" /><host><baseAddresses><add baseAddress="http://<ipaddr>/WebServices/" /></baseAddresses></host></service></services><behaviors><serviceBehaviors><behavior name="WebServices.MVSWebServicesBehavior"><!-- To avoid disclosing metadata information, set the value below to false and remove the metadata endpoint above before deployment --><serviceMetadata httpGetEnabled="true"/><!-- To receive exception details in faults for debugging purposes, set the value below to true.  Set to false before deployment to avoid disclosing exception information --><serviceDebug includeExceptionDetailInFaults="true"/></behavior></serviceBehaviors></behaviors></system.serviceModel><system.webServer><modules runAllManagedModulesForAllRequests="true"/></system.webServer></configuration>

The log file only shows me

2013-06-17 13:55:44 <ipaddr> POST /WebServices/MVSWebServices.svc - 80 - <ipaddr> ksoap2-android/2.6.0+ 500 0 0 2121

So I tried Failed Request Tracing on the server and I got (I can provide the full trace if necessary):

MODULE_SET_RESPONSE_ERROR_STATUS 

ModuleName IsapiModule 
Notification 128 
HttpStatus 500 
HttpReason Internal Server Error 
HttpSubStatus 0 
ErrorCode 0 
ConfigExceptionInfo
Notification EXECUTE_REQUEST_HANDLER 
ErrorCode The operation completed successfully. (0x0) 

Four days I'm banging my head against walls, any help would be appreciated :)

PS: I'm using Windows Server 2008 R2 with IIS 7.5