I know it's been over 2 years since you posted this question, but I too ran into the same problem and I believe the solution is to make sure that your camera type is a "Two-Node Camera". You can adjust this by clicking on your camera layer, then pressing command+shift+Y. At the top left (in After Effects CC) you will be able to select the type (either "one-node" or "two-node"). If it's set on "one-node" it doesn't require a point of interest to orient itself, and will therefore not have this as an adjustable option. You can read more about this here:
http://helpx.adobe.com/after-effects/using/cameras-lights-points-interest.h...
Specifically, it says:
"
Type
One-Node Camera or Two-Node Camera. A one-node camera orients around itself, whereas a two-node camera has a point of interest and orients around that point. Making a camera a two-node camera is the same as setting a camera’s auto-orientation option (Layer > Transform > Auto-Orient) to Orient Towards Point Of Interest. (See Auto-Orientation options.)"