Hi dop2000, thanks for your reply.
Well the layers are as follows:
Dune1 just has the first 'Dune1' sprite on it.
Dune1Tanks is the layer where the Tank is moved to when it reaches a certain travel distance.
Dune2 has the second 'Dune2' sprite on it.
Dune2Tanks is the last layer the Tank is moved to.
The Tank is moved to layers to make it go 'up' and 'down' visually.
Anyway, I tried your sample, but I think it is too complicated for me. Or at least, I don't quite understand it. Do I need to implement this code for each Dune sprite? As it goes up and down on two 'Hills'.
I also thought of and experimented with using a 'hitbox' sprite that is pinned to the Tank, had some ideas for it, but in practise I got so confused on how to implement it that I gave up for the moment.