My cat Eliot has fleas.

We took him to the vet last week and they prescribed Revolution. I've noticed dead fleas where he sleeps, and everyday I take a flea comb to him. For the past 3 days, there were no signs of any fleas on him...but today I found two live ones!!! Does this mean that the medication is not working? In addition, we have also treated and cleaned our house as best we could. Does anyone know what may be going on? Please help