when i adjust the saddle on my Les Paul the pitch never gets higher or lower on the 12th fret why..
Reword this please. I'm not entirely sure what you're asking.
Tempus Edux Rerum Sic Transit Gloria Mundi

Check out my band, Prosper! Prog/Metal/Core from Columbus, Ohio.
if the saddle is moving than the pitch HAS to change after the string is tuned back to pitch. what kind of tuner are you using? you should probably use a high end tuner for setting your intonation and not some pocket sized or pedal style one.
you know how you tune the string, then tune the 12th fret harmonic, and then you actually play the 12th fret note to see if its sharp or flat and the adjust the saddle thingys to fix it.

I do that but the actual 12th fret note never gets flatter or sharper when i do that