stuck to fastboot when try to flash recovery [Lenovo K3 Note]

Hello there, after an hour of search and no useful results, i've decided to ask my question (sorry, if it's already been answered, but i didn't find anything)

I used the following procedure to flash the CWM recovery, but something goes wrong:

( http://forum.xda-developers.com/andr...-note-t3102997 )

1. "adb devices" shows the phone correctly (At this state the phone is properly shown in my windows device manager)
2. "adb reboot bootloader" pushes the phone to boot in fastboot mode
... but ...
3 "fastboot devices" doesn't find it anymore. (At this state the phone is shown as an unknown device in my windows device manager)
4. after some attempts I tried "fastboot flash recovery recovery.img" anyway, but as I expected, i was unable to reach the device, the image should be written to.
5. every the phone stucks in fastboot mode, and the only way to restart it is by pulling out the battery.

So, what is the possible reason, to loosing connection to the device after the reboot in fastboot mode? (phone drivers already installed, pc rebooted, ADB SDK installed too)

Thanks in advance for any help!

Regards!