sigmake cannot unlock zte z970

SigmaKey v.2.14.03 build 01
426871453 Sigma dongle 2.14, Initializing…OK
Pack 1: Activated
Pack 2: Activated
——— 2015-12-29 16:00:52 ———
SigmaKey 2.14.03b1 ADB: Direct unlock
* daemon not running. starting it now *
* daemon started successfully *
^ ZTE Handset ADB Interface
Version: Linux version 3.4.0-g1af7f82 (xueyibing@scm12) (gcc version 4.7 (GCC) ) #1 SMP PREEMPT Tue Aug 18 23:35:33 CST 2015
Phone model: zte Z970
Android 4.4.4; Firmware: KTU84P; Date: Tue Aug 18 23:17:24 CST 2015
Version: Z970_MetroPCSV1.0.0B13
Baseband Firmware: .3.0.c9.6-00021-M8926DAAAANAZM-1
Obtaining root privileges…NO
Preparing….Reconnect phone and try again i see root good by vroot

SigmaKey 2.14.03b1 ADB: Obtain root privileges (Method #9)
* daemon not running. starting it now *
* daemon started successfully *
^ ZTE Handset ADB Interface
Version: Linux version 3.4.0-g1af7f82 (xueyibing@scm12) (gcc version 4.7 (GCC) ) #1 SMP PREEMPT Tue Aug 18 23:35:33 CST 2015
Phone model: zte Z970
Android 4.4.4; Firmware: KTU84P; Date: Tue Aug 18 23:17:24 CST 2015
Version: Z970_MetroPCSV1.0.0B13
Baseband Firmware: .3.0.c9.6-00021-M8926DAAAANAZM-1
Android Version: 4.4.4 "KitKat"
Obtaining root privileges………Failed