OPPO A71 Imei Banseband Is Ok ND Imei IS Null

[ateeq khan]

PTFN : MediaTek USB Port (COM102)
MODE : BOOTROM
PORT : 102
Waiting BOOT ack ...
BROM : Skip ACK verify
BROM : Init BROM
BROM init passed!
CHIP : MT6755 , SBID : 0x8A00 , HWVR : 0xCB00 , SWVR : 0x0001
TYPE : MODERN RAPHAEL
BROM : SecLevel : 0x00000000
BROM : SecMode : PLAIN [+PRL]
BROM : BOOTROM
BROM : SLA

BROM : Selected Auth/Cert not accepted by device!
Check previous message for more info!

When I Tried to repair Imei then give me this Error Anybody Help Me