Make sure you are inserting the core into the charger so that the charger contacts connect to the charger pins. The core should easily insert into the charger. If it doesn't start charging, then:
- Try a different USB port or UL-certified wall charger. Do not use a USB hub.
- Check for damage on the the charger pins
- If your tracker still won't charge, the tracker or the charger may be defective. Submit a request with the customer support.