I really don't understand this, but I think Emma STILL has fleas!

Before we got her, the shelter said she was treated with Capstar, and then a few days after we got her she went to the vet and they treated her with Advantage.

Last night I was brushing her and then I seen a flea(I think--it moved SO fast) on my leg , and Emma also scratches ALOT

I don't know why she would still have them