Check the Page Size
Ensure that the 'Page Size' setting in the printer driver matches the size of the paper loaded in the printer.
Then check the Page Setup dialog box for Macintosh. Open the Page Setup dialog box by clicking File and selecting 'Page Setup' from inside the application being printed from. In Page Setup dialog, select the size of the paper to be used from the Paper Size pop-up. To set a non-standard size, select Manage Custom Sizes.