Don't know if you have the same problem as I had but I had the Alarm function activated also when I was "testing" the level sensors by holding them down with my hand etc.
I had to go on the controller itself to LEVEL and the push the return button.
It asked something like "reset" or "reset alarm" and when I confirmed the alarm function went off and the sensor started working properly.
If there is no alarm activated and you would go on the controller to the LEVEL option and select it you won't see the "reset alarm" but instead you will see "operation mode"