Ran into this problem tonight with a couple expressions I've used in the past in CS3+. My scene has 1 camera. It it's set to active and the eyeball is on and its in/out is the length of my comp. Is 'activeCamera' broken in CS6?
These expressions are turning off:
delta = toWorld(anchorPoint) - thisComp.activeCamera.toWorld([0,0,0]);
C = thisComp.activeCamera;
V = C.toWorldVec([0,0,1]);
P = toWorld(anchorPoint);
lookAt(P, P + V);