Rumble function does not work on PSone titles

I was playing some PS1 titles, namely Alone In The Dark along with a few others, and noticed that the rumble, or vibration, if you will, is not there. I have turned on the Analog option and the sticks DO work. Just no rumble. Any one has a clue to this problem? I know some are tempted to ask "why are you playing a PS1 game on a PS3?" and the answer to that is simply because my PS2 is dying and it freezes quite often, and also, I would like to play the games on my LCD monitor which is placed much closer to me than my TV. So please no advices on playing the games on a PS1/ PS2. Thanks!