I am not an expert but from what I have been told it is true that scores at 7 years old are not very stable. The difference has to do with the statistical norming. For instance at 7 your daughter may have done significantly better than other 7 years olds (which is who she was compared to) but at her current age many of her age peers would have experienced substantial improvement in the way they have performed. So regression to the mean (which is what this is called) is pretty normal. It is not that your DD performed less well it is simply that other performed better at this current age than they did before.
