Games work on a normal playstation but won't play on ps one

[walkerdog]

I HAVE A PLAYSTATION & A PS ONE BOTH ARE MODIFIED THE SAME WAY; I PURCHASED THE NEW HARRY POTTER GAME AND MADE A BACK UP OF IT AND IT PLAYED ON THE PLAYSTATION BUT NOT THE PS ONE, THIS IS THE ONLY GAME THAT SO FAR DOESN'T PLAY ON THE PS ONE: IT MIGHT HAVE TO DO WITH THE LASER BEING SENSITIVE