Thanks for the response Jeff Kay. I checked and the expression does work on compositions. I made a test composition and it was fine. The composition I am animating does move from one point to another so this should work but it isn’t and don’t know why. The only thing I have done differently is to adjust the keyframe velocity. Would this have an effect?
FYI this is where I got the expression from:
https://docs.google.com/document/d/12ymsMLNA0oiIZc8_iXS9zuEMUH1NGV1zbvwnHkm21DM/edit