Issues calling a DLL from WCF/Silverlight

Trying to use a DLL that returns a list of tasks in the W2k3 server's Task Scheduler. Works great when I use it in a C# console app on the server, and using it on my computer (ASP.NET Dev Server), but when doing the same thing through the Silverlight-WCF RIA on the W2k3 server, it just wouldn't go. 开发者_如何学C Silverlight returned "Object reference not set to an instance of an object" whenever it calls that DLL.

Fired up the Service Trace Viewer:

System.ServiceModel.FaultException`1[[System.ServiceModel.DomainServices.Hosting.DomainServiceFault, System.ServiceModel.DomainServices.Hosting, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]], System.ServiceModel, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089

Might it because I'm using a DomainService class, its hiccuping? Any particular security permission or config on IIS that needs to be done?

update:

Tried one last thing .... Identity impersonation to my domain username and password works! So what is the best way to set up IIS to get this to work?

Just stuck with using a Windows dummy account using identity impersonation. Don't like it, but it works.