Can't get a PC to print using an AirPort Extreme

I'M USING A HP LAPTOP RUNNING WINDOWS 7 AND A HP OFFICEJET 5600 SERIES PRINTER HOOKED TO THE AIRPORT EXTREME USB PORT. I'VE LOADED THE BONJOUR PRINTER WIZARD AND IT SEES THE PRINTER BUT I CAN'T GET IT TO PRINT. EVERYTHING SEEMS NORMAL, THE PRINT JOB GOES INTO THE QUEUE, BUT NOTHING PRINTS. I CONNECTED THE PRINTER DIRECTLY TO THE PC AND IT PRINTS NORMALLY. THIS SETUP IS FOR MY PARENTS WHO USE A PC, I HAVE A MACBOOK PRO THAT PRINTS WITHOUT ANY PROBLEMS USING THIS CONFIGURATION. ANY THOUGHTS? THX.