web report

I have one strange problem with my web report that is being displayed on the portal.

Actually there is one button on my portal........when user clicks on it it displays a web based report which was created at the backend.The button calls some RFC for thsi purpose ....but my problem is that if the number of pages in my report is more than one there is no scroll bar appearing on the screen and if the user has to move to next screen then people having scroll mouse can scroll using mouse and move to next page.The keyboard keys has no effect if i hit page up or page down.

Where is the problem.............it is a standarad SAP report.Can we customize the area on the screen so that navigation to next page is possible using keyboard also........

please advise........