[Q] Can't enter fastboot. topic

Hi guys,

i've decided to finaly unlock my bootloader and flash a new rom, i thought maybe KitKat...
unfortunately i can't get into fastboot...i keep getting the dead android with red triangle.
tablet is working as usual, and i get the 3 options when trying to get into fast boot ( vol. down+ power)
but when i chose RCK it starts loading for a sec' and the dead android apears.

is this some kind of brick?
i have JB 4.2.1 OTA

i've search the forum & googled it, and i couldn't find a clear answer...

any solutions for this?
thanks!