I owned a droid incredible, the PRL number is 00000, I have changed it to be 10009, but after I restart the phone, the PRL number keep going back to 00000

detil my phone
Hardware version = 0003
HBOOT = 0.92.0000
RADIO = 2.15.00.07.28
Android Version = 2.2
Baseband Version = 2.15.00.07.28
Kernel version = 2.6.32.15gb7b01d1 htc-kernel@and18-2#1

Can anyone help me?