about GSM SIM900A module working and error with some AT commands

Hi everyone!!
I want to try sending sms and dialing a number using GSM module for a project so I bought a SIMCOM Sim900a GSM module and I have googled and got familiarised with its programming up to some extent.
Then I wrote a code to dial a number its not working.
All connections are properly set. Network led is also showing network.

So I want to test the module with reponses giving by GSM module so I wrote a code to read data and to give me response. then I tried different AT commands like
ATE0
AT
AT+CMGF=1
AT+GMM
all these codes showed me Gsm Working properly but when I actually type dail AT command its showing error that ERGSM not working .
I don’t understand what it’s saying soo plss anyone who knows reply mee fast …

I hereby attaching error list of some commands showed in serial monitor.(sorry for bad image)

Thank u guys!