Xpath constraint on templategrid

I have a TemplateGrid, with a custom "create new" button. When there is no Xpath on the templategrid, the grid gets updated correctly with the new object. However, when I put an Xpath constraint of [minutes-from-Datetime(createdDate) < 15] to show only the recently added objects (added in the last 15 minutes), after creating a new object the grid gets not updated with the new object. It doesn't show... Am i doing something wrong here, or should I start charging Mendix for my work as bug-tester for 4.0.1? :-D
1 answers

Got it. I was using the wrong Xpath function. Changing it to: [createdDate >= '[%CurrentDateTime%] - 15 * [%MinuteLength%]'] works for me apparently.