I'd ask the school. You can try calling the test maker, but I'm pretty sure they'll refer you back to the school. If I recall correctly, DD did have stanine 9 in all three categories. That would seem to mean that missing that one question on nonverbal meant the difference between an 8 or 9?

Not sure, I'm not the test expert round here! Based on what I've heard about the test in general, though, DS obtained an excellent score.