Hi Arslan,
If you don't mind me asking, how did you get communication to work? I've heard from most customers in the past that most USB to parallel port adapters do not work. I created a powerpoint presentation at Re: EVALUATION BOARD — AD9954 to explain the issue. I should probably convert that over to an FAQ at some point.
If you're also using a Windows 7 computer that compounds the issue as the software should only work on Windows XP. XP mode, which is free from Microsoft, won't work as it does not have access to the parallel port. However other Virtual Machine programs such as from VMWare can access the parallel port and do work.