Q2501 GPRS problem

Hello,

I have Q2501B with firmware 6.0sgg and I can’t make any GPRS connections.
I try to send below commands sequence:

at+cgdcont=1,“IP”,“www.idea.pl”
< OK

at+cgatt=1
OK

at+cgact=1,1
< OK

at+cgdata=1 or atd*99#
no response

I don’t receive no answer for command at+cgdata and modem is still remained in AT command mode. When I make the same operation on the Q2501B with firmware version 6.0kgg everything is OK. Could anybody help me to resolve this problem?

Thaks in advance
Grzegorz