I guess I need to pay more attention to my spelling and grammer :-)
The file you sent works fine, although when I open it in the developer, it gives me an error stating "Date calculations are not supported". I'm using Info 2010, but saving as a 2007 so that all can use it here. I guess it is possible my issue lies here.
You have used a section to contain your date picker wher I am placing mine into a recursive table field. I try to change the background color of the field. I'm attaching an example of what I'm doing.