SF2 - World Warrior Mame - Is it the PCB or ROM issue for Dragon Punch?

Hi guys...

I am new to this forum and hoping some of you can help me out...

I am big SF2 World Warrior fan... Found out about this MAME thing couple months back and started to do my homework on it.

Finally got MAME SF2 World Warrior running with my PC with 3 fight sticks.

1) Hori Real Arcade Pro v3 (Sanwa JLF - Round Gate)
2) Qanba Q4raf (Sanwa JLF - Round Gate)
3) Qanba Q3 Wireless (Seimitsu LS32 - Round Gate)

I use to play a lot when I was younger and have master all characters. I use to be able do Dragon Punch all day at any time and can still do it now on an arcade machine.

However... I can't say the same when I use the fight sticks I have at home.

I am having problem with the Dragon Punch for both Ryu and Ken. All the other moves are good for all other characters except for Dragon Punch.
*By the way, the Qanbas work very well for Guile, Blanka, E-Honda, and Chun Li (non circular special moves).

On these three fight sticks, I will need to hold down longer and tap the punch buttons split second later in order to successfully perform the dragon punch. This does not happen at the Arcade Machine which made me assume that the arcade machines were using the Seimitsu and not Sanwa.

So i bought a Seimitsu LS32 to test it out but the results were the same.

I am suspecting it could be either the ROM (which I have tried several different sources but same result) or PCB board that came with this fight sticks...

My next plan is to try out the iPac PCB board but am afraid that it could be something else such as the buttons or emulator instead.

Has anyone encountered this similar issue? Any idea what's wrong with it?

Please help... Thanks!