Why do I get the error message waitng for device in flashboot cmd?

I have read a lot about sloving the problem of the messeage <waiting for device> in the fast boot cmd, most of those ppl with the problem had it solved simplying by instralling the right driver, i know i have instralled my drivers right since i just unlocked my SONY XPERIA M bootloader (although i had to flash my phone since it was in boot loop after the process), now as i try to check if the flashboot is righty done by the cmd 'fastboot.exe -i 0x0fce getvar version' it says <waiting for device>. All i wanna do is get CyanogenMod in my phone.