Righteous defense with Taunt Master

Hello there.

I'm leveling ppala, and noticed that Righneous defense works not every time. I'm using Taunt Master, and Righteous Defense works not against every party member (ofc I use it only when they have aggro). E.g. it doesn't work against opposite faction players, which can be explained somehow. But sometimes it doesn't work even against my faction players, last time it was arms warrior. I mean he is close to me, all the mobs he have aggro against are close to me, but nothing happens when I push the button on Taunt Master.

Any ideas? Mby it is possible to set healbot to display aggro and use it instead of Taunt Master?