Custom media sizes not printing

[Paul]

I've been using an HP Deskjet 9800 to print 8.5x11 in. and tabloid media.  Recently, I had need to print on 12x18 in. stock.  Hplip provides for a "custom" media size, as confirmed by lpoptions.  The printer itself is capable of printing 13"x50".  The command that I'm using is:

      lp -o media=Custom.12x18in afile.png

Lpq informs me that the printer is ready and the new job is there, but it doesn't become active ... it just sits there.  There is no entry in the error log.

The file prints easily on 11x17 in. paper with:

      lp -o media=w744h1116 afile.png

Which is one of the options that pops up with lpoptions.

I'm running Fedora 7, CUPS 1.2.10 and hplip 1.2.7.

Am I mishandling the custom media option or is there something else afoot?

Paul