No answers... just sympathy. MY DD didn't cooperate on her testing either and the pysch really felt it was fear of getting something wrong that caused her to say 'I don't know' when she obviously had a pretty good clue.
We are opting not to do any testing for a year or two and see what happens. Maybe she will mature enough to make it worthwhile. Meanwhile, we are focusing on things like playing games and losing - but having fun anyway; trying new things that are hard; etc - trying to work on that perfectionistic streak that keeps her from really showing her stuff when she feels under pressure.
Good luck - and let me know if you find any magic fixes.
Mary
