DataWedge API Not Working

I am trying to add reference of DataWedge API into my .Net Project but I am getting error. My dev environment is Visual Studio 2008, Windows 7, .Net framework 3.5. I did try to create a dll from the tlb, even that is not working. Why cant zebra provide a dll file of the API ? If not what is the solution for it.  Need urgent support on this from Zebra.