GSM SIM900A not responding to AT commands!

im using sim900A in algeria/ north africa but its not responding to any AT command. its not reading any sim card nor responding to the AT commands and also it keeps displaying "power on/reset" when i tried to flash it with the SIM900 tool develop. iv found that sim900 is a global version while sim900a works only in india and im now testing it in algeria/ north africa. but if this was the problem, then why its not responing to the AT command. any help?

PS: i dont have any power supply problem!