Could it be that she gets the math conceptually, but hasn't had experience actually solving problems? DSs tester mentioned to us that he grasped above level concepts and could set problems up, but wasn't always able to complete the calculation. She felt it was due to not having the instruction yet. I do see that DS can do mental math far easier and quicker than he can do it with pencil and paper. Once he writes it down, he gets it all confused, especially if he's not had practice with it.
Just a thought.
This also reminds me of something Kriston said about not confusing math with arithmetic. Some of this mismatch may be ansynchronicity but some may be from not getting the opportunity to work at the appropriate level.
If Since DD is excited about the skip, I'd talk to her about the need to practice some of the arithmetic that's tripping her up with the local test.
