What I did get to work was that - according to selected buttons - the sprite approached.
So what I did was e.g. making a button in the "button choices"-section saying "Threaten", resulting in a range decrease (because threatening should not work with the ankylosaur...
)
But, as Manikus pointed out, it seems only possible to make the sprites work correctly in the Encounter-event. I have not found an auto-advance option there...
BTW, I did not post very much during the last month since there was some additional work to do, but I will find some time for DC in June, I hope...