My HCM11Z bluetooth module is not responding to AT coomands

while testing the Bluetooth module I came across with an issue, whatever commands I given through UART , the response is ERROR only, if I send any test commands with ‘?’ symbol, there it is working properly,
what might be the issue, how can I configure my Bluetooth module?, please help,

Can you share your email? Try flashing the firmware again. The problem is very strange.