Situation:
I created a GeneralBiztalkHelper Dll, I placed it in the GAC and want to use the assembly later in other projects.
When I wanted to add it to the new project via Add Reference, I didn't saw the assembly listed.
Solution:
The list of assemblies used in the Ad Reference dialog isn't populated from the GAC but from the following directory
%WindowsDirectory%\Microsoft.Net\Framework\%Version%\