huawei p9 lite flashing error

log
SigmaKey v.2.27.09
995249536 Sigma dongle 2.27, Initializing...OK
Pack 1: Activated
Pack 2: Activated
Pack 3: Activated
--------- 2018-03-10 23:12:27 ---------
SigmaKey 2.27.09 HiSi: Enable downgrade
Connecting...Error writing to serial port
--------- 2018-03-10 23:12:46 ---------
SigmaKey 2.27.09 HiSi: Write firmware
DBAdapter Reserved Interface (COM79), Provider: HUAWEI Technologies CO.,LTD, Driver ver.: 1.0.26.0, Date: 5/18/2016, USB\Vid_12D1&Subclass_13&Prot_23
Writing flash...UPDATE.APP
Firmware: VNS-L31C900B065
Hardware IMEI: 020304050607080
Writing flash SHA256RSA OK
Writing flash CRC OK
Writing flash CURVER OK
Writing flash VERLIST ...Version mismatch.
Use "Enable downgrade" action first, then retry flashing.
--------- 2018-03-10 23:14:05 ---------
SigmaKey 2.27.09 HiSi: Enable downgrade
Connecting...Reboot phone and try again
--------- 2018-03-10 23:15:17 ---------
SigmaKey 2.27.09 HiSi: Enable downgrade
Connecting...Reboot phone and try again