A few months ago I bought a Pet-Ease Pheromone Plus Diffuser for my IC cat, but after a month of being plugged in, the bottle of liquid was still full. I called the manufacturer, Nutri-vet, and they told me something must be wrong if the bottle was still full, so I took it back and got a refund. Thinking this was a one-time glitch, I then bought 2 more and have had them plugged in for a month now, but again the bottles of liquid are still full. The diffusers themselves are warm, so they appear to be working. Unless I missed some directions, I think I have them installed correctly--just remove the cap, screw into the difusser and plug in. I have been using Feliway diffusers for a long time and never had this problem. I plugged in a Feliway at the same time as the other two, and now the Feliway is almost empty. Has anyone else had this problem?