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Some coaches are bad at recruiting, and some are really good at it. Some coaches are bad at communicating - it doesn't mean they aren't interested. Some coaches don't communicate because they aren't interested. Some coaches have a lot of pull with admissions, some don't. Some sports are more important to certain schools than others, and so the sport has more pull in admissions. Your kid's value to the program will depend on the individual school's need at the time.
There are a lot of reasons why you may or may not be receiving the reception you mention, and trying to decipher why is difficult, and probably pointless. I would certainly re-send the email that wasn't responded to. I wouldn't copy the AO, as that is tantamount to tattling on the coach and may not be well received. If they remain non-responsive, then the coach is a terrible communicator or isn't interested. Either way, you should probably look elsewhere.
There are a lot of phrases bandied about on this site - some are horse doo doo and others may have some merit. One of those phrases should definitely be kept in mind and repeated often when it comes to athletic recruiting - love the school that loves you back. Even if you are successful in chasing a school that doesn't show you the love, your kid will have to fight an uphill battle against kids the coach loved more. Maybe s/he can overcome it, or maybe not. But wouldn't it be better to start out feeling like you are wanted?
Personally, I wouldn't want my kid to play for have a coach who is a poor communicator. What happens when college recruiting time comes around and a college coach emails the prep coach and is ignored? That certainly won't be helpful. The coach will necessarily be a point of contact throughout the prep school years. Do you really want your email ignored for four years? Because if they are ignoring your emails during the recruiting phase you can bet they will continue to ignore them once your kid is enrolled at the school.