my gc is nVidia 7600GT n my lcd is 19"SyncMaster 940BW.

My problem is, why is it i can't get 1400x900 resolution plus my lcd also dont have Auto Adjustment.when I pushed the button then a message gone out like this "Auto Adjustment Not Available".

Meanwhile, when I checked other 19"SyncMaster 940BW at LYP
then there is Auto Adjustment available + it gets 1440x900 resolution. Where actually the problems came from?