A Clock Question

[Smoke]

I do not know if this is even covered in the rules but last night at a game Black Teams scoreboard would go to all zeroes(it didn't have tenth)then about a second later the horn would go off. Talked to Orange Teams coach and he said the official said the timer was in tenths so that was the reason for the delay. I thought if a clock did not show tenths then once it reached zero the horn should sound? Any Feedback Thanks