Calendar Overlays

I have created a calendar where customers can reserve time with me and my team for various meetings.  I've created 2 overlays - 1 to show green when I have an open slot, 1 to show red when our time has been reserved.  I cannot get the overlays to function properly. I know it has something to do with the proper filter settings, but I haven't found the right combination to make it work properly.  

Basically, anything with text other than "OPEN SLOT" should be in Red, while OPEN SLOTs should be in Green.