"It is with sadness that we will have to decline the birthday party invitation for your son," one mother wrote me, "as such short notice was given." I felt like I had been punched in the gut. Again. You see, my son Casey has autism, and I had been busily planning all the arrangements for his seventh birthday party for weeks. I wanted to tell her, in earnest, that I had tried, I really tried, to get it right this time.