While Working on WCF i created a Duplex Channel Client but got this issue while try to open
"The InstanceContext provided to the ChannelFactory contains a UserObject that does not implement the CallbackContractType ."
The issue was clear from the description as in most of the cases for WCF.
So i simply have to implement the CallbackContract which in my case was IproductServiceCallback to the my class from which i was generating context.
This was in the generated proxy file from svcutil.