Aim function/constraints going haywire
 

For some reason when I select my rocket ship (following Mastering Maya Complete 2) and then shift+select my spot light and then choose Constrain-->Aim, my light does not follow my ship. Instead the light is locked on to some distant unkown point, and moves unwantedly when the ship moves. How do I fix this problem. I am experincing them same difficulty with cameras. I am using Maya 4.5 unlimited.

you may need to adjust the aim vector in the Aim Constraint's options. It's usually a value of 1 or -1 in X, Y, and/or Z direction.

As for it moving, make sure it's not somehow parented, keyed, or being affected by some sort of orient or point contraint.