Mouse Wheel Offset Problem

[dmwalker 604]

For some time, I have had a problem with using my mouse wheel function to rotate, for instance, the Altitude Knob in the PMDG B777. If I hover over the knob, I get the little hand symbols but the knob doesn't rotate. At a zoom of 3.0, I have to place the mouse pointer just below the Cancel/Recall button on the Display Select Panel in order to use the mouse wheel. At higher zooms, the offset location varies somewhat and, at lower zooms, it disappears.

It's not a PMDG problem because it happens with other aircraft as well. With PMDG aircraft, I use the alternative method of holding down the left or right button but some aircraft don't have that option.

Does anyone have any (polite) suggestions?

Thanks.

Dugald Walker.