Do you have a mousewheel that clicks down as the 3rd button? If so, are you holding it down while dragging?
Let's do a little test here. Go onto a webpage or something that has a lot of text. Now click the mouse wheel down once (not holding it) and see if you get that circle with the up and down arrow with the dot in the center. If you don't there's an issue with the mouse. If you do, then just move the mouse closer to you and away from you. Is the page of text scrolling?
If so, there's no reason why 3D should not work, maybe it's a driver issue but I thought all 3 button wheel mice were pretty standard nowdays.
Dave
EDIT: LCAM Manual in the Members Docs area:
http://www.machsupport.com/forum/index.php/topic,12078.0.html