Nearly FInished Cab - Just need the coin slot sorting - Help?!

[absvicandmark]

Hi, ive been up most of the night and have now nearly finished my neo geo cab conversion to mame. The software is working (though not setup exactly yet but is working satisfactory without kb and mouse), the monitor has been fine tuned to the best pic possible, the jpac and avga is setup a treat and the sound is all wired up and sounds fantastic.
Ive installed a credit button but also put a key lock underneath so I can turn off these feature if I want to (to get money!!!!). My coin slot is wired up and when I check the keypresses using winipac I can see the coin slot activating button 5 (p1 coin) when putting money in. However, when playing sometimes I have to put more than one coin in before it registers. I can put