keep the ar max disc in at all times until you go into launch game, THEN put in the mk:d disc.
and make sure you put in all the codes for the master code in properly, one wrong letter/number and it wont work.
and if its confusing, there are no O's used, only zero's, so if it looks like an O, it is a zero, i know for a fact they're zero's and not O's, not one code i ever put in used an O.
oh, and when you add a new game, that is where the master cod egoes, in case if thats what you meant.

thanx alot noob_sareena. im gonna try it now.

no problem, i'm glad to of helped!

can u do me a favor noob ? next time u use yer ar max, try the code to replace scorpion for sonya, jax, and nitara. the sonya and jax one said not a master code. nitara said something along the lines of not a valid action replay something. i have a feeling that i got a crap ar max

hm... maybe you have to put in the "modify scorpion into" sub-folder, since i know usually it wont work unless the sub-folder is in, then try putting in the cheat codes.
just when you get into the mortal kombat deception new game folder you create by putting in it's master code, just go into add new cheat and make the "Character Modifier/Replace Scorpion into:" code ( which is HZ3T-3QDV-560PJ just for easy reference), then go into add new code and put in the characters you want and the green test that says "Character Modifier/Replace Scorpion into:" or whatever, will change into a sub-folder containing the cheats you put in.

Ooooooooooooooooohhh. I just put the codes directly in. That's kinda embarassing.

lol, it's an easy mistake, it happened to me a few times before, though sometimes they actually worked but then they would'nt even be accessed, it's strange sometimes though, tricky at first but you get the hang of it.