Advice - Entered tenant unit without giving 24-hiuur notice.

[D T.]

Due to a some confusion, I let a foundation contractor into one of my tenants' units without giving the required 24-hour notice that I would need to enter the dwelling (my manager had at first said she'd notified the tenant who was at work, but there was a mix up). He was there for a very short time, then I locked up the unit. The tenant screamed blue murder that I let him in without her knowing (she's problematic). I've always let her know first if I need to go into her unit for repairs, etc., and even if I'm working at the front of, or side of, her unit. She's the kind that wants to make trouble; if that is the case here what do you suggest (I've apologized, and my manager also)?