Multiboxing 10man 2 x 5 man teams issues

[Swedishoyster]

So I'm trying to level up 2 x 5 man teams at the same time and got some issues. At first I was doing it in a 10-man raid but the exp you get is pityful and you can't complete most quests. So I took the advice from several posts in this forum and went with 2 x 5-man groups. I do however got some issues that wasn't present when in a raid.

Team 1 is a WMMMPr team and Team 2 is a PaMMLPr team.
Whenever I switch to my paladin tank who is the leader of group two, the assist doesnt work.
I target the mob, start attacking but the other 9 toons doesnt pick up the target.

I have a Pro setup and I've been using the standard Assist Me in Base Hotkey (ALT+A)
I doesn't work to press ALT+A with the mob targeted either.

Could someone pooint me in the right direction, been pulling my hair over this.

The assist work in normal 5-man and in a raid. I'm using the EMA add-on.