Try using the relevant property of the control in the initialize event.
ControlName.relevant = "-print"; // Forces an object not to appear when the form is printed, regardless of the object’s presence property setting
If you are using a reactangle to provide the background for the PDF then the above event will not be available. Instead convert the rectangle to Subform and set the fill color of the Subform.
If you still have issues you can post the file..
Thanks
Srini