>>>>I have a solution with two projects: NSPLogic and NSPWindows. NSPLogic is simply a collection of public classes that are used for business logic. I registered NSPLogic in NSPWindows references, but my forms don't see the classes. I put a using statement--using NSPLogic, but that throws an error when I try to run the project in debug mode. What am I doing wrong?
>>>
>>>The using statement needs to specify the entire namespace, and I'm betting that the namespace of the classes in your NSPLogic project is not simply "NSPLogic".
>>>
>>>~~Bonnie
>>
>>Nope. That wasn't it. Both projects have the same namespace. Could that be the problem?
>
>
>That was the problem. The classes were created in the same project then moved to a new project. I have to change the namespace.

Namespaces have nothing to do with projects so you don't *have* to change the namspace - just specify it correctly in the NSPWindows project. ie. this is perfectly valid:
In NSPLogic:

namespace NSPWindows
{ public class Class1 {} }

and, given a reference to NSPLogic, in NSPWindows:

NSPWindows.Class1 c = new NSPWindows.Class1();
//or just
Class1 c = new Class1();