I amusing a SIM 900A GSM module.When I tried to give HTTP commands it shows error.

AT+CGATT?
>OK
AT+SAPBR=3,1,"CONTYPE","GPRS"
>OK
AT+SAPBR=3,1,"APN","CMNET"
>OK
AT+SAPBR=1,1
>OK
AT+HTTPINIT
>ERROR

I checked

AT+HTTPINT?
error

Can any one help me to solve the issue?