Did you use a mixer (an immersion blender won't do it)? If there is even 1 drop of egg yolk in it, they won't whip. If the bowl or beaters are oily or dirty, they might not whip either. I can't think of anything else. It takes about 4 minutes from fridge to stiff whites in my Sunbeam Stand Mixer on the number 11 (very high) setting.