Issue found in the GWTService class method RPC_invokeAndEncodeResponse. The method finds the incorrect interface name with the  at the line. String serviceIntfName = serviceMethod.getDeclaringClass().getName();

This happens in the below scenario.
1. Create base service interface say X.java which has method sayHello().
2. Create two other serviceInterfaces Y.java and Z.java which extends the X.java.
3. Create two seam components for these interfaces.
then when you do remote method invocation for "sayHello" for the Y or Z interface it will try to search the component with interface name X insted it should have bean called for the Y or Z. depending on the service method invoked.

The solution to this may be include the method name as well as interface name in SeamRPCRequest and do not use the interface name from the method object as it's returning the base interface.