I just finished "Sands of Time" and wanted to get started with "Warrior Within" immediately. However, I'm' encountering a problem.

I can't control the camera, the way I used to do with "Sands of Time". I'm playing with mouse and keyboard, no joysticks connected.
I tried looking in control options, and I noticed there was nothing assigned to the "camera forward" etc controls. I'm guessing that's it, but I don't know how to assign the movement of my mouse to the movement of my camera. It's probably got something to do with y-axis, y-axis?
Or does the camera system simply work differently from the one of Sands of Time?
Any helps would be appreciated!