Problems coupling the Cadence sensor 2

Dear all,

I just purchased the Speed and Cadence Sensor 2 set from Garmin.

Installing the Speed Sensor was no problem at all.

My Garmin does, however, not find the Cadence Sensor 2. I tried everything according to the manual. It does blink after two revolutions, but my watch is not able to find the sensor.

I even changed the battery according to the manual.

Any advice?