I solved the problem.
In order to enlarge tne window an not to have cutting edges I made some changes according to this thread:
I did not realize that this will change the dimensions in all further piecemaker modules.
No wonder that it wont fit in the articles position. :-)
It were useful to change the code as the original is. So one can make the module dimensions a bit larger on the edges to see the full picture at the transitions.
So I wrote it back to the original code and it worked fine. Except for the edges.