"Connecting" speed sensors to Garmin 130 plus

[velobaba]

I am trying to connect multiple ANT+ (non-garmin) speed sensors to Garmin Edge 130plus. Garmin 130 plus detects the sensor and adds the sensor. But it is not able to "connect" it. Keep getting "Connection Failed" message on Garmin.
What's puzzling is that I am able to connect one of the sensors successfully. But can't connect any others.
These speed sensors are the one that came with the wireless Trek Incite speedometer.
And in the past, a year or so ago, I was able to connect all three sensors successfully. But now I can only get one to connect.
Any clues?

Thanks,
jalal