Gave my cats 2 proper doses of advantage, why am I still seeing fleas?

Found fleas so I gave my cats topical advantage II. 14 days later I still saw live fleas. Was able to give them a second topical dose. I am STILL seeing live fleas. Why is that? Is it normal? Or did it not work?

Id like go add no one has been bit by any fleas

and fleas only on the cats. not in our carpets and stuff

Best thing is to give them each a good bath. That will get rid of the fleas.

Advantage II is a monthly topical flea treatment. Please don't give it more often than that unles specifically told to by a vet. You don't want to risk harming your cat.

The label of Advantage II says it kills fleas witihin 12 hours. However that is just the adult fleas. Juvenile fleas and unhatched eggs are largely unaffected. A second or even third dosing may be needed. Again, this is monthly topical so you need to wait a full month before reapplying unless a vet has told you otherwise. In between dosings, vaccuum your home frequently to remove eggs off the floors and furniture (they're there, you just can't see them) and wash blankets and other things your cat sleeps or lies on in hot water. Comb your cat frequently with a fine toothed comb to remove eggs and any fleas. Bathing your cat is a good idea. You can attempt to do this yourself or have a groomer do it. A groomer can do a regular bath or a flea bath.

There are more tips on dealing with fleas here:

http://www.thecatsite.com/a/cat-fleas

the box said i could give a second dose if required 12 days later. I didn't blindly give my cats a bunch of flea meds. I in depth researched. 

Update: Seeing fleas. But no ones been bitten? I see them in the furniture, on my sisters bed too. But, no bites. The fleas are flat and barely move when I grab them and kill them.