Flea Treatment Not Killing Fleas

I'm hoping someone can give me some feedback on these flea treatments and which one they think is best.

The four main flea treatment available to me are Frontline, Advantage, Revolution and Capstar.  When I asked the vet assistant for a treatment, she told me a heap of info about each one and I ended up getting Frontline. From what I gathered, some of these include heartworm treatments and other things and some didn't.

My dog is 4.5 months old, 20kg (44pound), wormed and had a heartworm injection.  I was told not to get a treatment that included heartworm since my dog has already had an injection for that.  That is why I got Frontline.

I treated him on the 18th July and he still has fleas.  Has anyone else used Frontline and still found fleas? I read on another post that Frontline only stays on the skin and isn't absorbed. Could this be why it doesn't work as well?

Just an extra thought.  The first time he was treated for fleas he was 8wks no heart worm injetion so we used Revolution.  Never saw a flea on him after that.  He picked them up after a 'play date' when he was about 3.5. months. Our house had been professionally treated for fleas before we got him.

[Soon_to_be_DVM]

If there is fleas currently in your house that is where he is picking them up from.  I think frontline also takes 24 hrs to completely cover your dogs skin, but I have not heard of any problems so far with it. You need to treat your house. Your vet should probably have a SAFE spray to use on your house.  When an animal has fleas you need to treat the pet AND the environment! GOOD LUCK!