Idaho Antelope

I have been antelope hunting for about 3 years. Last year I was lucky enough to draw a tag here in Idaho and I shot a 14" lope. The year before I hunted with my bow and was never able to stalk close enough for a shot. The problem I am faced with is I went scouting for lopes last weekend in the same area that I bow hunted a couple of years ago. In this area I saw a good number of antelope each day I was hunting and was able to put on a few good stalks. While I was scouting in the same area I didnt see a single lope?! I know they didnt just leave so where could they be? This country is wide open and you can see for miles and usually I would see at least 20 a day just glassing....now the big 0..any info you guys might have would be great!
BrandonJ