GTA 3 Question for PS2?

Hi, i'm new on gamespot, Well I have GTA 3 for PS2 and action replay max or armax for PS2, and anyway, when i put codes on gta 3 a year ago using armax all of them seemed to work fine when i started the game, but now one year later, when i start the game with the same armax codes on it, some of the codes work and some of them don't, like the no car damage code works but the infinite armour and ammo codes don't, my PS2 is only 4 years old and it is the black slim version, i have tried using the ps2 armax memory card that came with the cheat disc aswell as the official ps2 memory card but some of the codes still don't work, the gta 3 disc was bought about 2 years ago which is around the same time i bought the armax disc, but i can assure you that there are no scratches or finger prints on the discs or PS2's disc tray, I keep my things in very good condition! but I can't find an answer to this anywhere and i'm getting really frustrated the way some codes won't work and i did not input the codes myself, they were already there when i got the disc, I have not tried the armax or memory cards with any other discs but i am positive that the memory cards are working fine as the gta 3 save i made last year loaded this year but i sadly deleted it when i started a new game and did not check if some of the codes were working on it, please don't call me a cheater, i just want some fun! by the way, I live in Ireland and have the PAl version of the PS2, The GTA 3 disc and ARMAX disc and i'm using the same PS2, GTA 3 Disc and ArMAX disc as I did last year!GTA 3 Question for PS2?
[This message was deleted at the request of the original poster]