HP Scanning Problem

I have HP 3055 All-in-one (scanner, fax, print). It is connected through network. When i tried to scan any documents or photos it gives a error as "there is no paper in the document feeder". One more thing which i found was, in choose scanning preferences - their is option called paper source: one as 'document feeder' & other as 'flatbed', in the system which i work i don't see the option of this flatbed. in all other systems the scanning is working fine, they choose flatbed and scan. but only in my system this problem is there. but print & fax is working fine. I even uninstalled the drivers and reinstalled it. i even scanned for viruses, there are no viruses in my system. pls help me out to solve this issue.