Team A's turn to serve. #24 is whistled to serve and coach of Team A trys to call a time out. #24 serves and Team A wins point. Then Team A calls time out. After the time out, #12 then serves for Team A and Team B wins the point. The REF then asks the scorekeeper if #12 was the correct server, which the scorekeeper says that #12 was the correct server but #24 was the wrong server. As the REF, what do you call, if any thing? Do you go back and take the point that team A got when #24 served? Is this a correctable error?