WCF RIA Service : underlying provider failed on open

I am using SL4 + RIA services class library + EF. Application should use windows authentication (LAN based). The scenario is, EDMX and RIA Services are deployed on machine A's IIS. If i am accessing RIA service from my silverlight application from same machine A it works. But, if i copy the silverlight project to the machine B and trying to access the RIA service methods deployed on machine A's IIS, then the RIA service returns the error as "underlying provider failed on open".

I have already implemented the Authentication domain service. I checked the ServiceContext.User.Identity, it return the proper windows user 开发者_运维百科ID, but while calling function import from ObjectContext it gives above error (underlying provider failed on open). RIA service is passing "NTAuthority\Anonymous" rather than authenticated user.

If anybody knows about this issue, Please help me. Thanks in advance

look if you have a cross domain policy issue. Ensure you have a client access policy file in the root of the website