Instruct: Classify Amazon reviews into positive or negative sentiment
Query: not working!!

I bought a 3 month supply from amazon for my kitten, and it is NOT working. I'm on month 3 and she still has fleas. She does not go outside, and I have a VERY clean house. I am not sure if this is a bad batch that amazon sent me, or if the fleas are immune to it. My dog uses it too, but he does not have fleas... so I am assuming it's a bad batch!