This one is driving me mad.

I've finished designing my report and I'm now trying to add a grid. Everything works beautifully until this I reach the final page of the report and there are no further records to display. I would expect to see only the fields defined in my Report Footer section. Instead the Box and Line object drawn in the Details Section continue to the bottom of the page over laying all the objects I've added to the Report Footer section. Does anyone have any ideas what's causing this?