well the thing is i can pull off things perfectly using a keyboard in Super Turbo which is 10x harder to do than SF4 because of the very very small window you have in that game.
what i mean is, if you are allowed 1 second to input the hadouken motion in SF4, you only have 0.25 seconds in ST (these are random numbers used purely as an example, not the actual values). i have no trouble using the keyboard even for that... it's almost as if SF4 is ignoring my input half the time.
i'm in a standing position with my ultra meter charged... and i hit qcf qcf lp+mp+hp. it doesn't come out. i try the exact same thing again at the same speed and it works. i can't seem to figure out why.
also, this might be a very stupid question, but you DO have your super meter charged before trying a super right? are you aware of 2 separate meters, one for ultras and one for supers?