Hi Gerhard,
Try using the T2-belegungskompatible Tastatur V1.05 source MSKLC source code file from
http://www.t2-tastatur.de/
Select the Startseite page, and then click on the "Nähere technische Information" link at the bottom of that page, you should then have a page with a link for the source code file.
That is what I've used and it works fine for me (I've just tried it again now and it builds on my machine). If this works and you can build the installer, don't forget to log out and log back in again to make it fully active.
The only other thing I can think of from Googling this is, if all else fails, try installing MKLC into C:\MKLC instead of into C:\Program Files\MKLC so that you now have a location without spaces anywhere in the directory names, just in case that is causing
problems.
Mike