Tray 5 may be ignored when trying to print on cardstock, even when the paper type for Tray 5 is set to cardstock on the printer AND the paper type is set to cardstock in the Xerox print settings on the computer.

The problem was a document setting that stays with the document even if printed on a different computer.

To fix

• In the Print box click Page Setup.

• Click the Paper tab. 
• Make sure First page and Other pages under Paper Source are both set to 'Default tray (Tray 5)' not 'Automatically Select'.
• Set 'Apply to' to Whole Document.