Hey Pinklady - my Miss 7 is pretty similar. Great speller when given lists of words to memorise, great story teller but not so great at writing. It's a difficult skill to master. I suspect there are a number of issues happening which might also be relevant to you:

* translating ideas onto words on a page where there is an obvious mismatch between the speed in which she thinks and the speed in which she writes;

* translating ideas onto words that are academically presented in the correct way - issues of editing, correcting, formatting, using punctuation, etc. and all those other things that get in the way of story telling. I just don't get why 7.5 year olds are tested via NAPLAN on the correct use of commas. What does that test exactly?

* dealing with perfectionism and disappointment that her great ideas don't come out "right" and don't look good to her;

Things that might help: touch typing, using drafts, using storyboards, getting the child to draw the story first (with minimal text the first time), being realistic about timeframes (a good story might take 1-2 weeks to develop), keeping an ideas journal; providing lots and lots and lots of opportunities to write without the pressure of staring at a blank page...

Any other things anyone can think of? jojo