Inactive SIM???? Help!!!!

Hi, I have a C902 which is on Orange. It was working with it`s original sim, but when I try to replace it with another Orange sim it shows "inactive sim" I tried the Aerix unlock from this site and it seemed to work successfully, but the phone still shows the inactive sim message. Incedentally it works with a T-mobile sim from another phone????

Can anyone help???? I am new to this, so treat me gently!!!

Thanks in advance for any help.

Try to unlock the "network lock" for all available frequency..