C# Shared dll help

Hi,

I am busy creating a networkbased program using C# and i am trying use Shared DLL for this.

I got the DLL fully working already but i got a problem.

The DLL has an interface MouseListener

I got a Connection object which implements MouseListener and has reference to the DLL
The DLL has a method called setMouseListener( MouseListener m );

now what im trying to do is to call the setMouseListener method whit as parameter a Connection Object.
but when i call it i get the following error:

Parse Error, no assembly associated with Xml key
a1:http://schemas.microsoft.com/clr/assem/ControllClient%2C%20Version%3D1.0.0.0%2C%20Culture%3Dneutral%2C%20PublicKeyToken%3Dnull Connection

Does anyone knows what causes this?

Thanks in advance