CUPS not printing via ipp: protocol

[Rich Lott]

I have two linux boxes, a debian one and a (k)ubuntu (dapper) one.

Both have cups 1.2.2 running. On the ubuntu box I've done the stuff to enable 
the cups web interface* and that works fine.

I'm trying to print from my ubuntu box to the debian one. This used to work 
fine, but today, the ubuntu box accepts the print jobs, and says 
it's "completed ok". The debian box's logs say similarly, but nothing is 
printed!

The debian box (connected directly to the printer) prints fine. 

The ubuntu box prints if I connect the it direcly to the printer (USB), but 
**not** if through the ipp://debianbox:631/printers/epson port. A windows box 
printing to the debian box (through http://debianbox:631/printers/epson), 
also works fine. 

So I think it's a ubuntu thing

Any ideas?

thanks,

rich

*enabling the cups web interface: Google to see what fun kubuntu users have 
had with kde printing admin interface not working, gnome's not installed (of 
course), and cups'  interface disabled by default! anyway, my cups 
http://localhost:631 interface works fine.