Sounds strange, but let me explain.
Initially, my GameController (Scene behavior) hat two public attributes: a
cursor<Actor> and
availbableTime<Number>. While designing the first rooms, I attached the Cursor-Actor to the attribute and entered the time via the properies tab.
So far so good, after I got the game mechanics technically working, I started to develop the game play and score bands for the stages and rooms. I did this using the good old paper and pen methods, not in Stencyl. After now having lots of lists, I decided to change my code to use this lists directly instead of changing the properties in each scene. To get rid of the cursor property also, I added the following lines:

So, instead of setting the
scene.Cursor via the properties tab, I look for a Cursor actor in the scene and assign it to the existing attribute. With my other code, I haven't changed anything.
So the cursor keys are still working and I can move the Cursor around.
But my cursor now stopped to detect collsions?

As I said, using the scene property (make it visible again) works perfect.
/very.confused.dripple