Do the following to make sure the Enable Single-Click Incremental Zoom-In option is selected:
Display a wheel that has the Zoom tool.
Click the Zoom wedge.
The magnification of the model is increased and you are zoomed in closer to the model. If you hold down the SHIFT key while clicking the Zoom wedge, the model is zoomed out; you can hold down the CTRL key to zoom in.
Display one of the Full Navigation wheels, or one of the View Object wheels.
Click and hold down the Zoom wedge.
The cursor changes to the Zoom cursor.
Drag vertically to zoom in or out.
Release the button on your pointing device to return to the wheel.
Display one of the Full Navigation wheels or the mini View Object wheel.
Press and hold down the SHIFT key.
Click and hold down the Zoom wedge.
The cursor changes to the Zoom cursor.
Drag the pointing device to define the opposite corner of the window that defines the area in which you want to zoom.
Release the button on your pointing device to return to the wheel.