How do i get Hadouken?

Let's review the procedure for getting Hadouken:

You must have all four upgrades, all eight heart containers, and all four sub tanks (and I'm pretty sure the sub tanks have to be full).

All eight bosses must be defeated.

I think you need to be at full health by the end of the stage (some guides mention this).

Finally, go through the armadillo stage, get to said area, pause and exit the stage from the menu; do not exit through the boss door. After the fourth or fifth time, an upgrade capsule should be waiting for you.

My guess is either the sub tanks are not full or you missed some heart containers. Oh and you're not going back to any other stages in between rounds, are you? Cause I'm sure that would screw with it too.