We have a Xerox 700 with Integrated Fiery Colour server. I send files from Indesign CS4 and I seem to be having a problem with the custom paper size. We print a lot of oversized A4 (225 x 320). The document size is smaller, but the paper size is set to this size. When the file arrives at the Command Workstation (5.3), the size often resets to 8.5 x 11. When I go back to the Indesign Print Dialogue box, and go through to the Fiery settings from there, the option is often greyed out.

Am I doing something wrong? Any help would be appreciated.