OK, I have a separate WCF RIA Service built as seperate project in DNN and compiled into the /bin folder
I have a Silverlight module (built using Codeendeavors Silverlight WAP template).

OUTSIDE of DNN, running the module in a test page, I can connect to the service. Once the SL app/module is IN dnn and ON a page, I get the error below. PLEASE SOMEONE EXPLAIN. I'm sure it has something to do with finding the .svc file and service definitions in the web.config file. ANY advice please.

Message: Unhandled Error in Silverlight Application
Code: 4004   
Category: ManagedRuntimeError      
Message: System.ServiceModel.DomainServices.Client.DomainOperationException: Load operation failed for query 'GetCategory'. An error occurred while trying to make a request to URI 'http://localhost/dnn_562/bin/MyCompany-RIAServices-RIADomainService.svc/binary/GetCategory'. This could be due to attempting to access a service in a cross-domain way without a proper cross-domain policy in place, or a policy that is unsuitable for SOAP services. You may need to contact the owner of the service to publish a cross-domain policy file and to ensure it allows SOAP-related HTTP headers to be sent. This error may also be caused by using internal types in the web service proxy without using the InternalsVisibleToAttribute attribute. Please see the inner exception for more details. ---> System.ServiceModel.CommunicationException: An error occurred while trying to make a request to URI 'http://localhost/dnn_562/bin/MyCompany-RIAServices-RIADomainService.svc/binary/GetCategory'. This could be due to attempting to access a service in a cross-domain way without a proper cross-domain policy in place, or a policy that is unsuitable for SOAP services. You may need to contact the owner of the service to publish a cross-domain policy file and to ensure it allows SOAP-related HTTP headers to be sent. This error may also be caused by using internal types in the web service proxy without using the InternalsVisibleToAttribute attribute. Please see the inner exception for more details. ---> System.Security.SecurityException ---> System.Security.SecurityException: Security error.
   at System.Net.Browser.BrowserHttpWebRequest.InternalEndGetResponse(IAsyncResult asyncResult)
   at System.Net.Browser.BrowserHttpWebRequest.<>c__DisplayClass5.<EndGetResponse>b__4(Object sendState)
   at System.Net.Browser.AsyncHelper.<>c__DisplayClass4.<BeginOnUI>b__1(Object sendState)
   --- End of inner exception stack trace ---
   at System.Net.Browser.AsyncHelper.BeginOnUI(SendOrPostCallback beginMethod, Object state)
   at System.Net.Browser.BrowserHttpWebRequest.EndGetResponse(IAsyncResult asyncResult)
   at System.ServiceModel.Channels.HttpChannelFactory.HttpRequestChannel.HttpChannelAsyncRequest.CompleteGetResponse(IAsyncResult result)
   --- End of inner exception stack trace ---
   at System.ServiceModel.DomainServices.Client.WebDomainClient`1.EndQueryCore(IAsyncResult asyncResult)
   at System.ServiceModel.DomainServices.Client.DomainClient.EndQuery(IAsyncResult asyncResult)
   at System.ServiceModel.DomainServices.Client.DomainContext.CompleteLoad(IAsyncResult asyncResult)
   --- End of inner exception stack trace ---
   at System.ServiceModel.DomainServices.Client.OperationBase.Complete(Exception error)
   at System.ServiceModel.DomainServices.Client.LoadOperation.Complete(Exception error)
   at System.ServiceModel.DomainServices.Client.DomainContext.CompleteLoad(IAsyncResult asyncResult)
   at System.ServiceModel.DomainServices.Client.DomainContext.<>c__DisplayClass1b.<Load>b__17(Object )

Have you looked as using a web service.

http://iweb.adefwebserver.com/  is a module for dnn that allows you to very easily add web service support to your site utilizing dnn security permissions.   You will still need to code methods for each database structure u want to expose - but its a good way to start.

Westa