Do not confuse the Paper Size drop-down menu in the Print Layout dialog box with your layout trim size as defined under Layout> Layout Properties.
Depending on your output purpose and method, the paper size should normally be bigger than your layout size to accommodate crop marks.
Jay Nelson is the editorial director of PlanetQuark.com, and the editor and publisher of Design Tools Monthly. He’s also the author of the QuarkXPress 8 and QuarkXPress 7 training titles at Lynda.com, as well as the training videos Quark includes in the box with QuarkXPress 7 . In addition, Jay writes regularly for Macworld and Photoshop User magazines and speaks at industry events.