Indiana Jones and the Temple of Doom (coinop) help

[CKF]

I was playing a few games I like that I know I can beat the score on, and saw Indiana Jones and the Temple of Doom (one of my favorites). I loaded it up, but when you try and add a coin, it says something like "source code limit: 1 credit", but it doesn't actually give you any credits, so you can't actually play it. It also gives out a bad/wrong ROM warning when you first load it up. Any ideas about this one? Thanks