Has anyone tried Plexer with more than 2 instances of WoW?

Currently I am trying to run 4 instances with not much luck. Basically from what I have seen, windows 1 and 2 on the list ALWAYS get the keys passed to them. And 3 and 4 only work if they're the currently active window.

I have 2 Folders. First one for the master, and second one with 3 duplicates of WoW for the slaves.

I don't think it's the method of using the "Enable Assistance Devices" or whatever because CloneKeys passes to all 4 clients just fine. And I don't think it's my computer. It's plenty fine running 4 instances.

Any one else experiencing this?