8007 PlayStation 1 Memory Card - Tips for writing user manuals

I'm playing FFVII on a PS2, and I'll save my game to the memory card, but when I go to load it, there is no data... I tried saving on 2 blocks, but when I did that, the first save had a bunch of glitches and weird characters for the time, etc. The same problem happens when I try saving my FFVIII game to the same memory card. I bought it from a used game store where it was guaranteed to work- is this a problem with the card, or do I need a Sony Playstation memory card instead of Mad Catz?