Any damage to the sensor would cause the device not to function correctly. The guarantee does not cover the battery, incorrect application, tampering, misuse or transport damage. Refer to the twelve month guarantee in the manual for more information. If there is no physical damage on the device it could be that the sensor is not making contact with your baby’s movement. Always make sure that Snuzas coloured flexible tip maintains constant contact with baby’s tummy. Refer to manual under section “Diaper/Nappy fitment” for more information. If the problem persists contact Customer Care by completing the form on the contact us page.