Thanks to Jumpy for getting this going (http://"http://visguy.com/vgforum/index.php?topic=1262.0"). If you want to calculate work weeks or calendar weeks of kalendarwochen, this article will tell you how:
Calculate Work Weeks For Your Visio Shapes (http://www.visguy.com/2009/11/03/calculate-work-weeks-for-your-visio-shapes/)