I ran the new 3D Camera Tracker in AE, which worked just fine. I selected the track points I wanted to use and created a Null object from those. As I scrub the scene, the null object stays perfectly in place within the scene, as it should.
However, I want to parent a JPG to that null, so that the JPG also stays in the same relative position as the camera moves, but the "parent" option doesn't take. The JPG stays at it's fixed position within the frame, not moving with the null.
Does that make any sense?
Provide a screen shot of your timeline.
One thing to check - does the JPEG layer have 3-D toggled? A 2-D layer parented to a 3-D object (like a Null) will not function correctly.
Well now, don't I feel pretty stupid.
The simplest things can really trip you up when you're not paying attention.