g935t unlock failed please refund my creadits

[ Unlock ] Operation: Unlock
[ Unlock ] Selected model: SM-G935T
[ Unlock ] Software version: 36.2
[ Unlock ]
[ Unlock ] Checking Login and Password... OK
[ Unlock ] Ballance: 21 crd.
[ Unlock ] You have 21 credit(s) left. This operation takes 8 credits.Continue? Yes
[ Unlock ] Waiting ADB device... OK
[ Unlock ] Reading phone info...
[ Unlock ] Model: SM-G935T
[ Unlock ] Android version: 7.0
[ Unlock ] PDA version: G935TUVU4BQG5
[ Unlock ] CSC version: G935TTMB4BQG5
[ Unlock ] Phone version: G935TUVU4BQG5
[ Unlock ] Product code: SM-G935TZDATMB
[ Unlock ] CSC country code: USA
[ Unlock ] CSC sales code: TMB
[ Unlock ] Phone SN: RF8H2216H2K
[ Unlock ] IMEI: 356164070878750
[ Unlock ] HW version: REV0.7
[ Unlock ] RF cal date: 2016.02.25
[ Unlock ] Chip name: MSM8996
[ Unlock ] Modem board: MSM8996
[ Unlock ] Security patch: 2017-07-01
[ Unlock ] Boot Warranty bit: 0
[ Unlock ] SIM State: ABSENT
[ Unlock ] Rebooting phone... OK
[ Unlock ] Waiting ADB device... OK
[ Unlock ] Rebooting phone... OK
[ Unlock ] Waiting ADB device... OK
[ Unlock ] Waiting for device to become ready... OK
[ Unlock ] Initialization zTool... OK
[ Unlock ] Running zTool, please wait... OK
[ Unlock ] Reading data from phone... OK
[ Unlock ] Rebooting to upload... OK
[ Unlock ] Searching Ramdump interface... COM10 detected
[ Unlock ] Reading data from phone... OK
[ Unlock ] Calculating... OK
[ Unlock ] Searching server... OK
[ Unlock ] Waiting for server answer... error (1)
[ Unlock ]
[ Unlock ] Operation: Unlock
[ Unlock ] Selected model: SM-G935T
[ Unlock ] Software version: 36.2
[ Unlock ]
[ Unlock ] Checking Login and Password... OK
[ Unlock ] Ballance: 13 crd.
[ Unlock ] You have 13 credit(s) left. This operation takes 8 credits.Continue? No