Here are a few possible causes and actions to take:

1. The pads don't stick to the patient's chest: Attach the pads to the patient's chest.

2. Poor contact between pads and patient: Check pads contact of patient.

4. Damage of pads, cables, or pads connector: Replace pads.

5. Damage of pads socket: Contact the manufacturer for maintenance. 

If you have questions about your device, please get in touch with your local distributors.