If your son is not playing summer ball for the school, I have your answer for you as to why he did not respond. If your son is not playing for him in the summer, he may see it as a slap in the face. When my son played travel and school had summer ball, he always made it back to as many games as he could even though it was not required. Coach did it for players who were not playing travel/showcase. But it spoke volumes when son showed up. The coach knew he was concerned about team and not just himself.