DLL file ........RCW

Hi...
I wrote a ddl (sample ) and few methods...
it is working fine ...
As COM is language interoperable....
I tried to call this DLL in C# in .NET ..
I got a Error Message saying that "it is not a dll" when i add refernce of this DLL...
Do i need to implement any interfaces in my dll to frame it as Perfect component.
Can anbody please guide me about this or links please...
Advanced thanks ....
Jaya...............

Have you written the DLL in VB6 or VB.NET? If its in VB6 then you need to read Interop services help section. I suggest you have a look at http://www.gotdotnet.com.