I am trying to calibrate but I don’t feel anything.

Confirm that the electrode liner has been removed and that the indicator light on the device has been blinking for at least 30 seconds. The purpose of calibration is to measure your sensation threshold, meaning that when you feel even the slightest sensation, you should  tap the button. Do not wait until the sensation feels strong to  tap the button. It may take 20-30 seconds to feel the sensation the first time and the sensation may feel very light. You will feel subsequent stimulation slightly faster. If you go through the calibration process and never feel stimulation (or  tap the button), the therapeutic intensity will be set at the maximum intensity.