Page Length in QR1

I am trying to set the page length of a QR1 report to 5.5 inches.
I have changed the paper size of the report component to qrpCustom and the
page length to 1397.
Problem is when I Preview the report all it shows is blank pages.
If I preview the report with paper size set to qrpDefault it looks fine.
What is happening here?
Is this a QR specific problem?
Matthew Pascoe.