Hi!!

Somebody please help me!
I am unable to set the APN on my iphone.
When I go into Settings -> General -> Network -> EDGE, I can type in the APN, but as soon as I come back to the network screen, the APN blanks out.
I have been able to change the APN before, but cannot do it now.
I am using iphone with firmware 1.0.2.

Please help. Appreciate it in advance.