Lane violation

[batreferee]

Situation: A1 is at the line shooting the first of 2 free throws. L bounces ball to the shooter to begin free throw. After ball has been administered and and instant before the shot, T notices that B4 is in one of the lanes spaces nearest the free throw line that should be unoccupied. T holds out his hand to signal a lane violation by B4. Shot misses, lane violation called and reshoot 1st free throw. B coach calls time out to discuss what the violation was. T informs him that it is not the responsibility of the officials to have them move. How you would you handle this situation.