ok, im not a total newb to photoshop but im stumped and desperately need help.

i bought an asus ep121 tablet. i have photoshop cs5 64bit running on it, i have the latest drivers installed, and i have brush dynamics turned on. and it set to pen pressure, but there's a small yellow triangle that shows up nest to it and pen pressure wont work. it doesn't matter what brush i use it just wont work, and i have all the options turned on, it also wont work in paint tool SAI. it will work on art rage and in alais sketchbook but just not in sai or photoshop

the specs of the tablet are
1.3 i5 quad core
4 gigs ram
64gig ssd
tablet pc.
running win7 64bit


can anyone help me please