Edge detected beyond the begining of the plate Lotem 400

Hi. Working with Lotem 400 .

The first exposition of the plate is correct. In the second exposition this error appear:

"Edge detected beyond the begining of the plate". Some problems with laser appear too.

Reset the machine and again have success with the first one. The second can not be exposed

I cleaned almost everything I think.
Sensors, Strip, Drum, holes.

Please someone could give me some advice about this problem.

Thanks on advance.