The left and right mouse buttons in the scroll bar not working

Hello. I've got Emacs 21.3.1
Normally, 'Mouse-1' should move the line up and 'Mouse-3' should
move down when clicking in the scrollbar.
In my case - bar is always moving only towards the mouse cursor.
What should I do to achive normal mouse behaviour?

Please email me directly.

Thanks in advance,
Yury.