I'm trying to set up a simple rule such that when @ is used in a new card comment, the person addressed would get added as a member of the card as well as myself. This way, we would both continue to get notified with any movement on the card.
I've set up the rule as follows:
"when @person-A is added to a card by anyone, add member @person-Ato the card, and add member @person-B to the card"
Here's a picture of that rule.

This rule never activates. I'm thinking the trigger doesn't do what I think it means...
Anyone have a clue what's going on here?