Non verbal IQ test

My son had a diagnosis of Specific learning disability when he was 10, the results of his test(BAS II) were verbal 88 (21%) non verbal 130 (98%). He did the fast forword program 3 years later and improved a lot at school, he did the Kaufman test at that time, he was 13 years old and he got a verbal of 93 (32%)and a non verbal of (87%).A year after we had to evaluated him again due that we are changing him of school. He did the WISC IV and got a Verbal 89 (37%), Perceptual Reasoning 100 (50%) Working memory 88 (21%) Processing Speed 83 (13%). I ask the doctor why his non verbal when from 130 (98%) to 100 (50%) and she told me that non verbal change with time, but I'm not satisfied with the answer as he was test last year and got also a very high score for that. Should I have my son test again? Can Non verbal decreases so dramatically??
  Thanks a lot for your help!

[Sandman2]

   I honestly can't remember if the Kaufman can be compared directly to the WISC IV.  It may be that the sub tests are testing different things.  A psychologist should know this.  I am not sure an MD would know.
   I do know that it takes a very good tester to get accurate results from a child with learning disabilities.  And if the WISC was done all in one time frame, that make it even more difficult to get accurate results.  Yes, you could have your son tested again.  But I would make sure you have a competent tester!
   If your child has ADHD, I have seen lots of sharp kids who score quite high on the nonverbal reasoning and bomb out on the rest.  The intelligence is there, its the processing that messes up the info coming in.  Hope this helps a little.