GROVE - PIR Motion Sensor & Yun

Hello, i try to make the demo sketch of the GROVE - PIR Motion Sensor (0.9b) working with the new Yun board but i can’t have it working. i try every tunes of the potentiometer but i could not get something stable. sometime it’s don’t react, sometime it’s react for nothing. can someone help please ?

no one can give me help ?