In the case of a battery sensor, check that the batteries are new and with the right charge. Not new batteries may not deliver enough current.
In the case of a USB type sensor, check that there is not too much distance between the sensor and the power supply. Make sure to use a USB cable equipped with ferrite and that the distance between the power source and the sensor does not cause voltage drops.
Verify that the transformer is capable of delivering 0.2 amps