Connect SIMCOM A7600C1 to Google MQTT


I’m using SIMCOM A7600C1 to connect to Google MQTT but I have a problem with that.
When send AT+CMQTTCONNECT, I got +CMQTTCONNECT: 0,27. It means “connection fused: unaccepted protocol version”.
Can anyone give me sone advice to solve this problem? or moudles can connect with Google MQTT.?