Never let the game go on until your signal has been answered by the scorers. On occasions you have to make two or even three signals involving just one delivery.
As an example consider this case – a no-ball is bowled which is missed by the batter, resulting in the ball hitting the stumps and flying to the boundary. Firstly, after calling no-ball, you need to signal no-ball and wait for the scorers to respond. You then need to signal byes to tell the scorers the ball was not hit and again wait for that signal to be acknowledged. Finally you need to signal the boundary four and again wait for the signal to be acknowledged.