O DB necessário para fazer o modelo do Aplicativo de Negócios do Silverlight funcionar?

Eu tenho tentado executar o modelo de aplicativo de negócios do Silverlight, mas ele falha quando tento registrar. Eu tenho o SQL Express com uma instância MSSQLSERVER e eu defini o aspnetdb padrão criado.

O erro é:

Submit operation failed.  Unable to connect to SQL server database.

 at System.Web.DomainServices.ReflectionDomainServiceDescriptionProvider.ReflectionDomainOperationEntry.Invoke(DomainService domainService, Object[] parameters)
   at System.Web.DomainServices.DomainService.InvokeDomainOperationEntry(DomainOperationEntry domainOperationEntry, Object[] parameters, ChangeSetEntry operation)
   at System.Web.DomainServices.DomainService.InvokeCudOperations(ChangeSet changeSet)
   at System.Web.DomainServices.DomainService.ExecuteChangeSet(ChangeSet changeSet)
   at System.Web.DomainServices.DomainService.Submit(ChangeSet changeSet)
   at System.Web.Ria.Services.ChangeSetProcessor.Process(DomainService domainService, IEnumerable`1 changeSetEntries)
   at System.Web.Ria.Services.SubmitOperationBehavior.SubmitOperationInvoker.InvokeCore(Object instance, Object[] inputs, Object[]& outputs)