I'm not chazz, but maybe I can help.

In my setup, I have an "Assist Me" keymap. Then I make a keymap for DPS, the first thing I do is call that Assist Me keymap (under actions, add one that is Key Map Action->Do New Mapped Key Action and select your "Assist Me" keymap

So for instance, if you are working on "character1". You would end up with "do assist me in character1 keymap->self" as the action.

Don't know if that helps or not...

I am also having a problem with my DPS key, but it's a different problem. I stacked 5 attacks with the longest GCD first, and shortest GCD last. When I call the key ingame, it keeps casting the same one over and over (the shortest one) even though the cooldown is not up on the others. I put each attack as a separate action in one step. Should I have made each one a different step instead?