screening question

[coachwithaquestion]

Hey folks, we play under NCAA rules.

A6 has ball at top of key. B10 defending. A4 steps in right behind B10 - who cannot see A4. A6 then dribbles. B10 tries to back up, but A4 is in the way. Is this legal? Referee told me no call.

The rule book says: "A player shall not cause contact by setting a screen outside the visual field of a stationary opponent that does not allow this opponent a normal step to move."

Thanks for the info!