How'd We Do?

[bc7]

7th grade Bantam game today.
Team A is shooting a 1-and-1, upon missing the first free throw neither team goes after rebound, shooter grabs the ball and while in the air to shoot the ball the scorekeeper buzzes the horn thinking it was 2 shots, and trying to get a sub in. The basket goes in, we say it counted.

Team B calls timeout. During the timeout team B coach is arguing that his team stopped because of the horn, and it should be blown dead and Team A's ball OOB. I tried to explain to him that the horn was not the reason IMO that his team stopped, it was the failure to play the miss on the 1-and-1. Shockingly he didn't agree with me.

Assistant coach on Team B is a fellow referee and he tried telling me that this is a correctable error, and during the timeout we can change it. I explained to him that I didn't think we made an error.

Obviously this all could have been averted had the scorekeeper not buzzed the horn, but it was an honest mistake.

Did we make the correct call, or should it have been ruled a dead ball?

Thanks in advance.