We had similar issues with my 6 year old son. His achievement test numbers on the WIAT III were much higher (140,145,160, etc.) than his IQ scores on the DAS II (129 on verbal the highest). We thought he had ADHD but have since changed schools to a much faster paced curriculum. He is doing incredibly and the best part is that he is completely off medication.
For him, the issue is a connection to meaningful material. He wont play along unless the topic interests him. Perhaps it is the same for your son?
Good luck!
