Troubleshoot in the following order:

1. Check if the microphone is powered on and has sufficient battery (the most common cause).
2. Check if the receiver or speaker is turned on and plugged into the correct port.
3. Ensure the microphone and receiver are set to the same channel/frequency.
4. Try turning both devices off and back on again.

If the issue persists, please contact our hotline via [Zalo/Fanpage] for assistance or warranty support.