Some plants or trees may have zero electrical variations at certain times and therefore do not emit any musical notes. Try stimulating it by touching the leaves or stem near the sensors. You will find that some plants sing a lot and others almost not at all. For example, cyclamens sing a lot, while orchids sing very little. If the silence persists with all plants, try touching the two sensors simultaneously with both hands. If they do not emit music, then there is a problem, so contact us at the appropriate form or email support@plantsplay.com