Thank you!!!! I do not have the guide - only the help file. (I had searched in the installation folder, and googled, to see if I could find any additional
documents and failed to find this guide.)
You are correct: I was making the mistake of trying to set the "laws of changing" on the first key frame, but I also tried on the subsequent key frames with no success there either.
Today, on reopening, it works perfectly. I am good to go!
Many thanks for your help, and the AL5 Guide.