ok.. just a mere Anon internet user here...
though he already know the answer, he still didn't post it here..
so for the sake of those who don't know...
just use "Keys - Send Keystrokes" instead of "Keys - Hotkeys"...
then input "[ALT_DOWN][TAB_DOWN][ALT_UP][TAB_UP]" of course without quotes...
and just a reminder to those new to using "Keys - Send Keystrokes", always put an UP for every action or else the button will be always held down virtually...