IR sensor GP2D12

I have an AT89C5131 microcontroller and i would like to recieve the value from my sensor and display it on the lcd. My sensor is connecter to LM324 and the LM is connected to P3.3.

my question is how to recieve the value of the sensor and display it on the lcd in centimeters.

my LCD in connected to P0.

i have uploaded my program and here is the download link:

http://www.mediafire.com/?tnggzmm5lgj

all it does is to show me 000 on the screen

please help me to figure out what is wrong with my program.

thank in advance,

Boris.