WCF 500 error on IIS without logging to Event Log

I have faced to odd error, does anybody know what this means? This service works normally from VS2010 but breaks on IIS. Unfortunately i could not google what is the meaning of this error code...

Module  ManagedPipelineHandler
Notification    ExecuteRequestHandler
Handler ExtensionlessUrl-Integrated-4.0
Error Code  0x800703e9

Trace for WCF looks like :

<system.diagnostics>
    <sources>
      <source name="System.ServiceModel"
              switchValue="Information, ActivityTracing, Critical, Error, Warning"
              propagateActivity="true" >
        <listeners>
          <add name="xml"/>
        </listeners>
      </source>
      <source name="System.ServiceModel.MessageLogging">
        <listeners>
          <add name="xml"/>
        </listeners>
      </source>
      <source name="myUserTraceSource"
              switchValue="Information, ActivityTracing, Critical, Error, Warning">
        <listeners>
          <add name="xml"/>
        </listeners>
      </source>
    </sources>
    <sharedListeners>
      <add name="xml"
           type="System.Diagnostics.XmlWriterTraceListener"
           initializeData="D:\Trace.svclog" />
    </sharedListeners>
  </system.diagnostics>

And result of the tracing :

<E2ETraceEvent xmlns="http://schemas.microsoft.com/2004/06/E2ETraceEvent">
<System xmlns="http://schemas.microsoft.com/2004/06/windows/eventlog/system">
<EventID>131073</EventID>
<Type>3</Type>
<SubType Name="Information">0</SubType>
<Level>8</Level>
<TimeCreated SystemTime="2011-12-02T12:52:40.5061619Z" />
<Source Name="System.ServiceModel" />
<Correlation ActivityID="{00000000-0000-0000-0000-000000000000}" />
<Execution ProcessName="w3wp" ProcessID="3584" ThreadID="2" />
<Channel />
<Computer>ANAZAROV</Computer>
</System>
<ApplicationData>
<TraceData>
<DataItem>
<TraceRecord xmlns="http://schemas.microsoft.com/2004/10/E2ETraceEvent/TraceRecord" Severity="Information">
<TraceIdentifier>http://msdn.microsoft.com/ru-RU/library/System.ServiceModel.Diagnostics.AppDomainUnload.aspx</TraceIdentifier>
<Description>AppDomain unloading.</Description>
<AppDomain>/LM/W3SVC/3/ROOT-2-129673033336784854</AppDomain>
<ExtendedData xmlns="http://schemas.microsoft.com/2006/08/ServiceModel/DictionaryTraceRecord">
<AppDomain.FriendlyName>/LM/W3SVC/3/ROOT-2-129673033336784854</AppDomain.FriendlyName>
<ProcessName>w3wp</ProcessName>
<ProcessId>3584</ProcessId>
</ExtendedData>
</TraceRecord>
</DataItem>
</TraceData>
</ApplicationData>
</E2ETraceEvent>

Thanks, Art

ANSWER IS FOUND !!!

This extension needs to be installed : http://support.microsoft.com/kb/2468871

You can enable tracing on your service and then check the place where your web service is failing. To enable tracing follow this link. Also try to invoke the web service from IE and see what the stack trace says. Else post the stack trace for more help.