Alert Issue - Triggering at incorrect times

I've run into an issue with a couple of my alerts, and the options I've tried are not working. The alert I am having an issue with is set to email when event 4728 occurs that has a certain group in the event message. My original format was EventID 4728 and message contains Group One.

This was working fine until someone added Group One to another AD group. In reviewing the event messages I found that the easiest way to achieve this would be to specify when the message contains TargetUserName Group1. However I can't get this to work.

Is there a way to get an alert to only trigger when the TargetUserName is Group One? I appreciate your time and any assistance anyone can offer. Thank you.