I'm trying to configure a Silverlight Business Application with Silverlight 5 using OpenRIA at VS2013. i'm facing a big challenge.
1. There was no Silverlight Business Application Template. Some How After doing R&D I got it which Uses Open RIA.
2. When I tried to Use Entity Framework 6 with Oracle Devart After Adding NuGet package for it ADO.Net wizard doesn't allow to proceed. So i moved with Devard Wizard. Got Added.
3. Now I Tried Using WCF 5.6 Data Service No success Yet. Doesn't work at all from 5-6 weeks.
4. Now I tried Using Domain Service No Template Available After Updating Template Appeared.
5. Now I'm adding This Service No Domain Classes Show on wizard to select. Don't know come later they appeared out of the box after doing many times.
6. When it appeard added 1 service now.
Error	2	'System.Data.Entity.Core.Objects.ObjectSet' does not contain a definition for 'AttachAsModified' and no extension method 'AttachAsModified' accepting a first argument of type 'System.Data.Entity.Core.Objects.ObjectSet<HPMModel.WEBUSER>' could be found (are you missing a using directive or an assembly reference?)	D:\hpmsweorkspace\hpmsapp.Web\Service\HpmsDomainService.cs	49	13	hpmsapp.Web

issue appeared.
So as a whole Now I'm confuse. What I'm doing wrong?

I've an requirment like this:
I've to Build an ESRI application whose Spatial Data is In Oracle 11g it comes from Different sources. Each module interact with different Data. My Cilent want Rich appliation so we choose Telerik Silverlight UI. 
What is the best template to Use? what should be the Architecture Can Any Body Suggest Please help. I'm messed up between VS2013, DevArt, WCF RIA, Domain Service, WCF service & Validations too?? 
waiting for Kind reply.
Thank you