My personal experience, and it is just that, with my daughter was this...I wasted my time going to the school before I had an outside eval. done. Unless there is a financial problem or a testing problem ,I would get an outside eval done and then approach the school. First because an outside eval is going to be much more extensive. We spent five days some of which were 4 hour days testing and discussing results with the pediatric psychologist that did my daughters testing. The school spent and hour for one session and about a half hour on another aspect, done. Yes, they will do their testing but then you already have an understanding of what is going on and what you want to advocate for. Secondly, the school district did testing last year, limited testing at best and decided that my daughter was fine based on those tests. The CASL test is commonly used and is a very poor test with gifted children. Because of there intelligence they often test above average on this test which in the case of Aspergers can be very misleading and just plain wrong. My daughter was denied services which is when we had an outside eval done. After much prodding the school purchased the PLSI test this year. It accurately states that my daughter tests in the poor to below average range in pragmatic language skill and, fingers crossed, according to the speech therapist should receive services this year.
I also discovered that the people who are supposed to understand aspergers don't necessarily understand gifted aspergers. That would be my reasoning. May I ask, how old is your son?