When Do I Walk in?

[jkumpire]

I was down in HS Varsity match last night, with a well-established quality partner up.

S99 is CF, and also the setter for S.

R hits a ball that S99 returns, and my partenr immediately calls a back row attack, and gives the point to R. I know he's wrong.

Of course the coach questions the call, and S99 who is the captain says to my partner that she is up front. After a moment, my partner gives a replay, and we all live happily ever after.

My question is, if my partner had not reversed her call, when do I as the umpire step in and ask my partner what he has, and tell him he might be mistaken?

I have my opinion, I am looking for some guidence from the big dogs here. .