The way your post is framed, it sounds like you wrote your c# frontend using the K2.Net 2003 API, or you are at least trying to re-use some of the same codebase from the previous version. If this is the case, you need to download the Developer Reference documentation (just came out a couple of weeks ago) and use some of the many code examples available in there to connect to and use the K2 server. In the documentation there is a section called "About Accessing Processes" which will give you all of the detailed step you'll need in order to access process lists using the [blackpearl] API.

Hope this helps!

endpointsys