DQ mess up

[so cal lurker]

Foul called on Blue 3. Double bonus. After white 4 makes the first free throw, R tells blue coach that was his fifth foul. Coach argues that the free throw can't count because he was entitled to 30 seconds to replace the player who fouled out before the free throw was taken, and therefore it needs to be retaken.

I'm guessing that, not withstanding the lawyer's, er, coach's creativity, that since the coach was not informed it was the 5th foul that the 30 second period never started and the FT stands -- but curious what the actual answer is. (I couldn't hear the dialogue between the ref and the coach, but that is what I inferred was the answer given by the R.)