ThinPrint - Printer mapping but not printing?

Hi all,

I have setup a thinprint test enviroment. It is setup to map a particular printer to a particular thin client based on IP information.

The printer is mapping but I can't print to it. The print job just sits in the queue as "printing".

I have opened following ports on the firewall:

TCP 515: LDP
TCP 631: IPP (Internet Printing Protocol)
TCP/UDP 9100: HP Jetdirect

Do I need to open any other ports or did I forget to do something else? I browsed the Horizon View Admin guide but it doesn't say anything about ports in regards to Thinprint.

Thanks!