Pay no attention to umad. That’s a troll account.
Anyways. There’s a shortcut system built into SFIV that isn’t explained in ANY of the game’s documentation. The game is so unabashedly lame with all the stuff it doesn’t tell people.
The dragon punch motion for most characters isn’t :r:,:d:,:df:.
It’s Any :r:, Any :d:, Any :r:.
The sheer number of DP motions in this game due to this is mind-boggling. Couple this with the input leniency – The amount of time the game will store previous inputs for the purposes of activating special attacks – and you end up with really easy DPs.
There’s roughly 35 different motions for DP in this game, not including motions that have more than the three directional inputs required for DP.
What you’re probably doing is moving from :df: or :r: too fast. The input leniency sticks around for a while, so you’ve got to sit either in Neutral or Back for a moment before you try the Shakunetsu motion.
Certain characters with reverse DPs like Adon and T.Hawk don’t have shortcuts on their moves, surprisingly. Fei Long does, though. It’s dumb.
Anyways. Once you get your execution solid, you’ll be taking advantage of shortcuts all the time. So don’t throw up your arms in defeat yet. Just keep playing.