In mouse properties ensure the checkbox for vertical scrolling is selected, and that it is set to scroll a certain number of lines in the wheel tab of the mouse properties.
If still not working I would then uninstall the driver and restart, letting windows use it's built in mouse control driver. If it still doesn't work I'd suspect a problem with the mouse.
The basic features of mice like the scroll wheel should be plug and play, meaning the scroll wheel should work properly in another computer without even installing the drivers. Can you try plugging it into another computer?