Has anyone tried Sentinel?

I am trying to find a flea control for my bullies. She had a horrible reaction to promeris. Frontline and Advantix don't seem to be helping. We spray the carpet and back yard every 2 weeks....Help!!!

Our vet gave it to us for Maggie

But she's only gotten it one time so far so I'm not the best one to answer. Seems to be working though.

Our lab is on Advantix, and it works for him.

All three of mine are on it.