Error flashing A255

[mdpm]

Hello, I unlcoked a LG A255, but now I need to repair imei, and always get invalid protocol error, so I decides to flash it, but get error to...

LGE Tool version: 1.54
OS Version: Windows XP [NT 5.1] Service Pack 3
Administrative privileges: yes
Locale: Spain / Spanish
CPU frequency: 1814 MHz
Total memory: 2013 MB
Free memory: 1150 MB
Free space on system disk C:\: 28.00 GB
Free space on disk D:\: 11.00 GB
You have slow cpu. Correct work can only be guaranteed on cpu with frequency 2 GHz or more.
Flashing firmware from D:/Flashes/LG/Setool/LGA255AT-00-V10a-722-YYY-JUN-17-2011+0.sbf
Preparing loaders
Disconnect battery and connect cable to the phone
CPU: PMB8815 rev. 1
Software Platform: X-Gold 215
Device found
Sending preloader
Sending loader
Setting up configuration
Looking for GPT
Dumping security area
IMEI: 357668-04-xxxxxxxx-x-00
Creating backup in: Backups\A255_35766804xxxxxxx_x.sbf
Protocol: Invalid response: at address 0x74518000