[Q] Unable to Flash

Try to flash my Acro S, but not success.. anybody can help me? What did i miss out?

in my phone Rooting Status :
Bootloader unlocked: Yes

18/035/2014 12:35:24 – INFO – <- This level is successfully initialized
18/035/2014 12:35:24 – INFO – Flashtool Version 0.9.11.0 built on 2013-06-04 22:50:00
18/035/2014 12:35:31 – INFO – Device connected with USB debugging on
18/035/2014 12:35:33 – INFO – Connected device : Sony Xperia Acro S
18/035/2014 12:35:33 – INFO – Installed version of busybox : N/A
18/035/2014 12:35:33 – INFO – Android version : 4.1.2 / kernel version : 3.4.0+1.0.21100-313065-g1ccebb5-00166-g58b3171 / Build number : 6.2.B.0.211
18/035/2014 12:35:36 – INFO – Selected Xperia Acro S_LT26w / 6.2.B.0.211 / KernelOnly
18/035/2014 12:35:36 – INFO – Preparing files for flashing
18/035/2014 12:35:36 – INFO – Please connect your device into flashmode.
18/035/2014 12:35:41 – INFO – Device disconnected
18/036/2014 12:36:21 – INFO – Device connected in flash mode
18/036/2014 12:36:22 – INFO – Opening device for R/W
18/036/2014 12:36:22 – INFO – Start Flashing
18/036/2014 12:36:22 – INFO – Processing loader
18/036/2014 12:36:22 – INFO – Checking header
18/036/2014 12:36:22 – INFO – Ending flash session
18/036/2014 12:36:22 – ERROR –
18/036/2014 12:36:22 – ERROR – Error flashing. Aborted
18/036/2014 12:36:22 – INFO – Device connected in flash mode
18/036/2014 12:36:30 – INFO – Device disconnected
18/036/2014 12:36:42 – INFO – Device connected in flash mode
18/037/2014 12:37:10 – INFO – Selected Xperia Acro S_LT26w / 6.2.B.0.211 / KernelOnly
18/037/2014 12:37:10 – INFO – Preparing files for flashing
18/037/2014 12:37:10 – INFO – Please connect your device into flashmode.
18/037/2014 12:37:11 – INFO – Opening device for R/W
18/037/2014 12:37:11 – INFO – Start Flashing
18/037/2014 12:37:11 – INFO – Processing loader
18/037/2014 12:37:11 – INFO – Checking header
18/037/2014 12:37:11 – INFO – Ending flash session
18/037/2014 12:37:11 – ERROR –
18/037/2014 12:37:11 – ERROR – Error flashing. Aborted
18/037/2014 12:37:11 – INFO – Device connected in flash mode
18/037/2014 12:37:16 – INFO – Device disconnected
18/037/2014 12:37:34 – INFO – Device connected in flash mode
18/038/2014 12:38:09 – INFO – Please connect your device into flashmode.
18/038/2014 12:38:10 – INFO – Opening device for R/W
18/038/2014 12:38:10 – INFO – Processing loader
18/038/2014 12:38:12 – ERROR – No loader found for this device
18/038/2014 12:38:12 – INFO – Your phone bootloader cannot be officially unlocked
18/038/2014 12:38:12 – INFO – You can now unplug and restart your phone
18/040/2014 12:40:19 – INFO – Device connected with USB debugging on
18/040/2014 12:40:20 – INFO – Connected device : Sony Xperia Acro S
18/040/2014 12:40:20 – INFO – Installed version of busybox : N/A
18/040/2014 12:40:20 – INFO – Android version : 4.1.2 / kernel version : 3.4.0+1.0.21100-313065-g1ccebb5-00166-g58b3171 / Build number : 6.2.B.0.211
18/048/2014 12:48:45 – INFO – Selected null
18/048/2014 12:48:45 – INFO – Flash canceled
18/049/2014 12:49:26 – INFO – Log written to C:\Flashtool\flashtool_2014-02-17_12-35-24.log