H871 AT&T unlock PROBLEM!!

Hi ..i got this error while try to unlock ...

Checking phone at COM5
Detected ID: 00001010 (MSM8996)
SW Version: MPSS.TH.2.0.1.c3.1-00028-M8996FAAAANAZM-1.167449.1.182474.1
Reading ESN... OK
Read SPC...
SPC: 000000
Unlock SPC... OK
Backuping RFNV... OK
Backuping Feature Mask... OK
Backuping NV Item... OK
Backuping NV Item SIM1... OK
Backuping NV Item SIM2... OK
Backuping Provisioning Item Files... OK
Phone mode is NORMAL
Switch to DOWNLOAD mode
Phone detected!
Read security zone...
Laf Protocol: 01000009
Model name: LG-H871
Software verion: H87121m
Android verion: 8.0.0
Target operator: ATT
Target country: US
Chipset: msm8996
IMEI: 355470081038719
Save part1...
Laf cmd info: send LAF_CMD_READ, retry #1
Laf cmd info: send LAF_CMD_READ, retry #2
Laf cmd info: send LAF_CMD_READ, retry #3
Laf cmd error: LAF_CMD_READ could not write.
Laf cmd info: send LAF_CMD_KILO, retry #1
Laf cmd error: LAF_CMD_KILO invalid response.
Laf cmd error: LAF_CMD_KILO invalid response.
Elapsed: 382 secs. --> (v9.61)


Maybe the firmware version is not supported ???? ...please HELP!!!