Getting a Cat to Stop Spraying?

I have 4 cats. They got along famously until I bought a kitten 4 months ago. All of them are used to her now accept one who is really annoyed, as she is constantly chasing him, so he spits and loudly hisses. He has been fixed, as are all the others and my new kitten was fixed two weeks ago.

Today I noticed he sprayed urine, so I am assuming he is really stressed. I had a spare bottle of Feliway and have it plugged in. It has worked within 24 hours in the past, but will it work for this?

Thanks.

By Joan from Toronto, Ontario