The event Unit stops casting is fired when channeling stops, whether interrupted or the duration is successfully completed. The event Unit finishes casting fires only when the duration completes. Alternately, you could periodically check whether the unit's current order is still the order of that spell.
Hopefully you can see how to use those in your spell, but if you need more help, we'll need to see your current code to be able to advise you further.
I'm on a page about incorrect corrections, and spent the better part of like two hours trying to get someone to understand that -5^2 = -25, not 25, and then that post had comments get reposted because that group is self sustaining, and that person was in turn trying to explain what I just explained to them. And I'm taking that as a victory
I will be AFK for a couple of days you guys hold down the fort while I am gone. I will be checking in on my phone but that will severly limit me. Be back saturday!