Unity OpenCV Crash Fix

My Unity OpenCV Document Scanner App is crashing after a few minutes an I don't know why. I can't debug it, I couldnt find information in the unity log nor in the logcat. My tries to fix every possible memory leak didnt worked out. I switch from a cheap opencv version to the expensive one, without success. Is there an Unity/OpenCV Expert out there? It's not enough to know something about Unity - you need to know stuff about OpenCV ;)