I was having a problem trying to save PSX info on my PS2 memory card, but it wasn't working on my PS2. Is there a compatability problem with PS2 cards and PSX games? do I need an old school PSX memory card to save the info even on the PS2? Or am I just not doing something right with the PS2 memory card?

PS2 cards won't work with PSX games.

You have to use a PSX mem card to save the game.

PSX games/cards work in a crappy block system, whereas PS2 games save in a much better system, so they're not interchangeable.