high quality printing does not work

hi,

I have a hp970 printer connected via usb to my linux-box. The Windows 2000 
clients can print via ipp, that seems to be no problem, but when I switch the 
quality to high, the printer only prints one small piece in the upper-left 
corner and then nothing more happens...

In the logs I have read something about "Media tray empty!"... This is, 
however, not the case when I print in normal quality

Sorry for my bad english, but what is the problem?