Dear New-
I hesitate to venture a guess at whether your child is more highly gifted than the test showed, but it does sound as though he wasn't really focused on the tasks at hand. Let me share my experience with testing a four year old, and maybe it will help you.
I have two PG sons. My daughter always seemed to be right up there with them in intellect, and when she was 4.5, we paid to have her tested by a private psychologist. My daughter performed outstandingly for the first 40 minutes or so, scoring at the levl fo a child well over twice her age on a picture vocabulary test and hitting ceilings on two subtests on the WPPSI. But then she SHUT DOWN. She refused to speak or answer a single question more, and a snack break and time with Mom did nothing to change her behavior. We left that day without completing the test.
Two years later, we had medical testing and found out that my daughter has an issue with reactive hypoglycemia. Sugar makes her hyperactive and then when she crashes, she gets very taciturn and moody. Protein is her best friend, and if she doesn't have it throughout the day, she becomes unbalanced. That fateful day when she was four, I treated her to a breakfast of DONUTS and cocoa! No wonder she petered out! Her blood sugar was crashing.
We did get another evaluation when dd was six. This time, she was very cooperative, and she scored well into the PG range. She was also diagnosed ADHD, which I believe is a valid diagnosis for her. She is in constant motion, except if she's reading, and even then, she tends to flop around a lot.
Good luck-
