The sensor will not capture left-handed data if it is connected to a right-handed club.  Double check that you are connected to a club with the correct handedness.  If you are connected to a left-handed club and the sensor still is not capturing data, if may be because:

-A ball is not hit (you must hit a ball).

-Swing time is longer than 2.0 seconds.

-It is a chip or pitch shot under 30 mph.

-It is a putt that does not have enough quiet time at address (holding the putter still at address for the blink of an eye).

-The sensor is misaligned (the head of the blast logo on the sensor is not pointed down the center of the shaft towards the toe of the putter).

-The putt was made on a slick or tile surface (and did not have enough quiet time).

-The putt was made with only 1 hand (and did not have enough quiet time).