Weblogic web service security -- error:5000 Invalid security

One of my client created a web service client by .NET want access my service protected by message level security. Once set the response is signed and encrpted the .NET client can not go through, and my weblogic server generates error message (error code: 5000, Invalid Security). Spent couple days to dig, found the problem is because the client using "EncrptBeforeSigning" which is not recommanded by Oracle Weblogic.