Possible causes:

1. Analog TVs: These require a digital receiver converter. After obtaining the converter, you need to perform a channel scan on your TV through the converter.

2. Channel Scan: Digital TVs must be programmed to receive digital signals. After connecting the antenna, scan for TV channels. Ensure that the channel scan is completed before installing the antenna to determine the best installation location.

3. Aerial Antenna Installation: If the antenna’s installation angle is not in the direct line of sight of the broadcast tower, you may need to raise the antenna or relocate it to different positions. Ensure the antenna is not obstructed by physical barriers. Remember to perform a channel scan after each relocation.

4. Outside Antenna Range: Depending on the distance from your location to the signal broadcast towers, you might need an antenna with a longer range.

5. Coaxial Cable Disconnection: Check all cable connections and ensure they are free from moisture, corrosion, and rust.

6. Indoor Antenna Installation: Building materials such as brick blocks, metal facades, and plaster can significantly reduce signal reception. If you experience signal issues with an indoor antenna, move it outside. Ensure that outdoor antennas are not obstructed by buildings, hills, etc. Perform a channel scan after each relocation.