Trouble with network printer install

[Robert Krueger]

Hi,
I thought this would be fairly simple, but I guess not.
I'm trying to install our LaserJet 2600N Color printer that's on our LAN as IP 192.168.0.4. (in Umbutu 6.06 ) I checked in WinXP, and it's using port 9100.
So I simply did an "Add Printer", and used the recommended syntax:

ipp://192.168.0.4:9100

nothing...

Then I tried socket://192.168.0.4:9100

nothing...

I give up, what's the secret here?
Can someone help?

Thanks,
Robert