webservice error

Hi,
I am running a silverlight 4 application which is using web services.
The folowing error occurs when trying to create an instance of the web service.
Can you see why this is occuring please?

Error:

xxxServiceClient _xxClient = new xxxServiceClient();

The invocation of the constructor on type 'xx.xxx.Silverlight.xxxx.somename.somenameData' that matches the specified binding constraints threw an exception. [Line: 13 Position: 41]

Any thought please?
Thanks

I think you should post some more code...

The more accurate error is:
Unrecognized element 'message' in service reference configuration. Note that only a subset of the Windows Communication Foundation configuration functionality is available in Silverlight.

Any thoughts please?