Point at will do what it says on the tin, it will make the camera point at the origin of some item, but it will not change the orbital centre of the camera. There is a difference between 'Pointing At' and and 'orbiting'. When a camera orbits some point it will maintain a constant distance from that point, when it points at some item the distance between the camera and item can vary enormously, depending in the position of the item and the rotation of the camera.

To change the the point that the camera orbits, you should follow richardson's advice. In recent versions of Poser, an alternative to parenting the camera to an invisible prop is to use the 'Frame Selected Object' feature, which you will find in the Camera Controls palette. Using 'Frame Selected Object' will cause the camera to orbit the position of the  item  selected at the time you apply 'Frame Selected Object', but note that it will also alter the position of the camera. To maintain the position, Memorize the camera first, then after using 'Frame Selected Object' Restore the camera. You will have changed the orbital centre, and still have the same camera position.

Personally I usually use richardson's method. I have nothing against Point At, it is good for what it's meant for, but it does not change the orbital centre of the camera.