AES Question MVS slot 4 RAM error?

I went to play a AES cart (original) on one of my NEO GEO AES (Japanese) systems and 3 times (with the same game) I had a message show saying "MVS slot 4 RAM error" and the chim on the NEO Boot up screen was odd sounding.. why would this be? Any help would be great

Cheers!

Josh