more info please. what are you brewing in? a bucket? how long ago did you pitch the yeast? what has been the room temperature?
if your brewing in a bucket its perfectly normal for the airlock to not bubble. the CO2 is escaping elsewhere. all the airlock is is a pressure release valve not a fermentation indicator.
its also possible you just haven't waited long enough for fermentation to begin. each fermentation is different. just because one starts within an hour doesn't mean the next will. it can take a few days before visible signs of fermentation start.
if the room is to cold the yeast will be sluggish and take longer to get started and finish. for typical ales the wort itself should be 68F with the room being slightly colder to account for heat produced by an active fermentation.
if your curious put your good ear up to the side of the bucket. if you hear a hissing then you know fermentation is going on. also you can take a SG reading. if its gone down from the OG then you know there is fermentation.
my over all recommendation is RDWHAHB.