N920A 5.1.1 Write imei done, But imei not change, still old imei

Operation: Write CERT
Selected model: SM-N920A
Software version: 26.5

Waiting ADB device… OK
Reading phone info…
Model: SAMSUNG-SM-N920A
Android version: 5.1.1
Product code: SM2N920AZKAATT
Phone version: N920AUCU2AOI6
PDA version: N920AUCU2AOI6
CSC version: N920AATT2AOI6
CSC country code: USA
CSC sales code: ATT
HW version: REV1.0
Phone S/N: RF8H52SL2HY
Modem board: SHANNON333
RF cal date: 20160526
IMEI:
Checking Super user right… true
Initializating zTool… OK
Running zTool, please wait…
Start… OK
Init… OK
Generate and check client proof… OK
Verify proof by client… OK
Reading data… OK
HWID: 68 EB 79 CE 76 07 00 00 00 00 00 00 00 00 00 00
Initialization AT RIL…
AT RIL stopped, restarting…
Checking for compatible phone and cert
Phone KEY ID: 0448
Checking certificate file… OK
KEY ID: 0448
Reading nv data… OK
Checking NV data… OK
Calculating… OK
Writing nv data… OK
Rebooting phone… OK
Write CERT done
Done with Samsung Tool PRO v.26.5