Silverlight WCF service calling exception

A Silverlight 3.0 application tries to call WCF service but the application can not even establish connection to the endpoint. I had checked URLs etc. and every thing seems ok. Accessing the service from other tools like browser works. When I debug application in Visual Studio when the first call to the service is made below output is dumped:

'sllauncher.exe' (Silverlight): Loaded 'C:\Program Files\Microsoft Silverlight\4.0.50401.0\System.ServiceModel.dll'
A first chance exception of type 'System.IO.FileNotFoundException' occurred in mscorlib.dll

When the 开发者_Go百科above error happens, application starts to wait until timeout.

Also Silverlight application is Out of Browser one with elevated permissions set to true so no need for crossdomain.xml.

I wonder if the above System.IO.FileNotFoundException can be detailed by doing something? Or may be you may have come up with this problem.

Thanks anyway.

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It was an issue of calling WCF service from a high level at App.xaml.cs, the problem is gone when called from MainPage.xaml.cs.