Vampire Savior has a problem when performing luminous illusion with Lilith, and Darkness Illusion with Morrigan. If button 4 is connected via the JAMMA edge and the kick, you will not be able to perform the move despite inputting the correct button combo.
The way to test would be to pick lilith, get your special meter up to at least 1, then do: LP LP FORWARD LK HP quickly.
Doing it correctly will result in a special move. Doing it incorrectly, or with the JAMMA button 4 connected, you will stand there like an idiot doing normal moves.
Four years later to say thanks, but thank you for this information. It saved my sanity. I got a good deal on a VS board a few months back, but became busy and just got to throwing in an Open Key over this last weekend. Morrigan is my main who I use all the time when playing at Mikado or on my Switch. I'd say I can nail Darkness Illusion about 80% of the time in training and maybe 60% of the time when I need it during a match; not the best, but can still perform it often enough. For Finishing Shower, I can do it over 90% of the time in training and probably 80% of the time in a match.
Anyway, after the VS board came back to life I of course wanted to do a playthrough. Both Darkness Illusion and Finishing Shower would not come out at all. I thought maybe it's just been a while, so lets make 2P join as a dummy. Still nothing. Just to satisfy my curiosity, I put on VS training mode via Switch Capcom Fighting Collection. Nailed both moves over and over and over again over 90% of the time. My stick can connect to both the Switch and supergun at the same time, so I even had both screens going at once. Move came out on Switch, but not on CPS2 lol. I know there's got to be SOME timing difference between platforms, but that much would just be absurd. I also figured something had to be wrong on my hardware because I play on Astro City cabs at Mikado about twice a month and don't have the problem. The last way that I knew something had to be up was because when I performed Cryptic Needle the move came out on both platforms over 90% of the time. That move only uses punches, so I figured the problem had something to do with the 4th button as it's the only one the two problem moves (Darkness Illusion and Finishing Shower) share.
Anyway, fast forward to me doing some Google Kung Fu and stumbling across your post, and problem is now solved. I immediately went "ah shit that's right, there's switches for this stuff". Disconnected button 4 from JAMMA and I can now do both moves. Thank you again!
Typing the below phrases for anybody having the same problem searching Google (hopefully they come here):
Darkness Illusion not working CPS2 ; Darkness Illusion not coming out CPS2 ; Can't do Darkness Illusion CPS2 ; Darkness Illusion hard CPS2 ; Darkness Illusion real CPS2 hardware
Also, below is a good training exercise to get better at this move:
View: https://www.youtube.com/watch?v=6VM5mDAgTho