I am attempting to control the camera with the arrow keys in Portal 1. I bound the arrow keys to the 'Turn Left and Right' and 'Look up and down' commands in Settings, but when I tried to play, I could only turn left and right, looking up and down didn't work. I tried rebinding the keys, using the developer's console, and restarting Portal, but nothing worked. Portal works fine, and I can move with my mouse.
Is there some special command or binding I have to use, or do the Look Up and Look Down commands not work at all?