I have similar issue with Hikvision DS-HD1 3MP WiFi doorbell camera. I've tried two chimes, one 3 terminal, the other a 4 terminal. Both chimes ring only when doorbell is pressed, but not when the doorbell button is released. Thus only the "Ding", no "dong". BTW the DS-HD1 is successfully connected to Hikvision DS-7608NI-I2/8P