So I discovered that the xml file of the function library contains a hard relation to my local HD, that pretty much explains why Performance Center cannot find the libraries, because it still refers to my local HD. So I made the exact same directory location of the load generators with a copy of the libs and now Performance Center can find the libraries.
OK, now I bypassed the problem, but surely this is not the way how to do things.
If anybody can tell me how it should be done properly I sure would like to know...
Regards,
Peet