It may be explained by:
A weak radio signal
If your Sensor is too far from your Smart Indoor Camera or an obstacle, like a concrete wall, is separating them, it is possible that your Sensor cannot properly transmit data to the Camera. Be sure that your Camera is close enough to where you want to monitor with your Sensor.
Verify the batteries of your Sensor. When inserting the batteries in your Sensor, you should see a green LED blinking at the top of the Sensor. If you think that the batteries are empty or that you are not sure, we recommand you to replace them.