My dd10, whose IQ scores are rather high, didn't do that well on the CogAT either. Like your dd, her scores were above avg, but nowhere near her WISC-IV scores.
For us, the timed aspect was an issue (it is only timed from 3rd grade on). Other issues included the testing circumstances (in a group with people having walked in and out of the classroom during the testing -- I was there waiting to go in and volunteer and saw parents going in an out and apologizing loudly to the teacher for having not seen the sign on the door) and that dd is very divergent in her approaches as others have mentioned.
The CogAT is not an intelligence test. It bugs me to an extent that schools use it that way. The publisher clearly states that is is testing abilities kids have developed not their intelligence or innate ability. I realize that it is the best they can do due to cost constraints, but it doesn't do the best job narrowing down high achiever vs. gifted and doesn't work well for a certain segment of the gifted population.
