Rotoscoping Issue - It works only on first frame and adjustment not working too

Dear all,

I am using the Rotoscoping tool in one of my projects.

Unfortunately it only works on the first frame!

If I want to select the object a few seconds later it creates a pink frame around the whole shot!

And also if I choose the object on the first frame and hit space bar so that the propagation starts I cannot adjust anything anymore becuase it ignores the tool after the first frame!

Anyone an idea what I am doing wrong?