Connect a PrintString node to Cast Failed and see if it prints anything when you place the potion into the coffin. If not, then the issue is in the collision settings. Make sure neither the potion nor the coffin trigger is set to ignore the other.
Connect a PrintString node to Cast Failed and see if it prints anything when you place the potion into the coffin. If not, then the issue is in the collision settings. Make sure neither the potion nor the coffin trigger is set to ignore the other.