Using .NET DLL in Powerbuilder application

Guys,

I've wrote one DLL using VC# .NET. In this DLL the actual function is inside a class(by default everything you develop in VC# in one class) inside a namespace.

Lets say name space is X, class name is Y and actual function inside class is Z then how would I invoke the DLL in the powerbuilder? powerbuilder is not able to find function under the
name space and class. Does anybody has any idea how do can invoke this DLL in powerbuilder.

Thanks