A starnge problem occured when I was trying to add reference to one of my WCF service in my silverlight project. When deeply researched I found that some of the data contracts have been references twice in the reference.cs i.e. some classes with version 3.0.0.0 and some with 2.0.0.0 version. Strange!!

A quick work around was to generate the reference via svcutil.exe and it worked well in case where the project was justa relay service and not the silverlight application. In silverlght app, it throws the error for async and completed methods. Then I used SLSvcutil.exe i.e. svcutil for silverlight which is bundled with silverlight 3 only. I used this and generated the refences.cs for me. One problem left is FAULTCONTRACTS in the code. That i removed manually and it is working now.