Bests & Worsts Reviews from Amazon

We have a 3 and 10 year old new-to-each-other female cats. We put the regular Feliway in each of their main rooms, where they each spend most of their time. Then we put one of the Multi-Cat plug-ins in the main part of the house. Once we noticed them spitting and hissing more than they had been and I checked their plug-in and discovered that I had put in the regular Feliway instead of the Multi-cat. Once I exchanged it, they calmed down within a few hours. I also tried to use just multi-cat instead of the regular one in my cat's main room and she became noticeable more playful, almost aggressive or intense. Since that's the only thing I had changed, I switched back to the regular one in her room and she calmed right down again. So, I can't say I totally understand why that would happen, but we seem to now have to combination figured out, and we can't change anything. So, I guess we are sticking to it, at least for a little while longer. Now, if someone could figure out how to make pheromones to help people get along better. :)