AT+KTCPCNX=1 Error on HL7800

We are issuing the following commands but cannot establish a connection:

-> AT+KCNXCFG=1,“GPRS”,“m2minternet.apn”
<- OK
-> AT+KTCPCFG=1,0,“8.8.8.8”,80
<- +KTCPCFG: 1

OK
-> AT+KTCPCNX=1
<- ERROR

Any idea what we are doing wrong?
Thanks

Hi,
1st step should be to activate Termination Error
Send AT+CMEE=1 in order to replace ERROR response by a +CME ERROR: x with x a number which meaning is indicated in the AT command user guide