System Workbench for STM32

After I reinstall the ST-Link over the Device Manager. I have a new ERROR:

10:52:53 **** Programing project t2 on chip ****
"C:\\Ac6\\SystemWorkbench\\plugins\\fr.ac6.mcu.externaltools.openocd.win32_1.8.0.201603291052\\tools\\openocd\\bin\\openocd.exe" -f stm32f3discovery.cfg -s "C:\\Ac6\\SystemWorkbench\\plugins\\fr.ac6.mcu.debug_1.8.0.201603291114\\resources\\openocd\\scripts\\st_board" -s "C:\\Ac6\\SystemWorkbench\\plugins\\fr.ac6.mcu.debug_1.8.0.201603291114\\resources\\openocd\\scripts" -c "program Debug/t2.elf verify exit"
Open On-Chip Debugger 0.10.0-dev-00267-g884c33c (2016-03-16-12:22)
Licensed under GNU GPL v2
For bug reports, read
http://openocd.org/doc/doxygen/bugs.html
Info : auto-selecting first available session transport "hla_swd". To override use 'transport select '.
adapter speed: 1000 kHz
adapter_nsrst_delay: 100
Info : The selected transport took over low-level target control. The results might differ compared to plain JTAG/SWD
srst_only separate srst_nogate srst_open_drain connect_assert_srst
srst_only separate srst_nogate srst_open_drain connect_assert_srst
Info : Unable to match requested speed 1000 kHz, using 950 kHz
Info : Unable to match requested speed 1000 kHz, using 950 kHz
Info : clock speed 950 kHz
Info : STLINK v2 JTAG v27 API v2 SWIM v0 VID 0x0483 PID 0x3748
Info : using stlink api v2
Info : Target voltage: 2.907583
Error: init mode failed (unable to connect to the target)
in procedure 'program'
in procedure 'init' called at file "embedded:startup.tcl", line 473
in procedure 'ocd_bouncer'

• OpenOCD init failed **

shutdown command invoked

10:52:54 Build Finished (took 197ms)

May someone knows the cause?