Hi maya1234, is your child outgoing or shy? A bit grumpy or very smiley?
My daughter finally got into a good school (she is older now) but from when she did the assessments (she did 2 in north london schools, she did not get in in any of them) I noticed one thing: there is something about some girls (confidence, but more than that) that makes it really easy for them.
Sometimes I am one of the parents at my daughter's school for when the girls do the4+. I play a little game with myself. I talk to the parents (normally only a few any given day) and then I put their daughters into the "yes", "maybe" or no pile.
Then come September, I normally see some of the yeses (some might have gone to different schools, etc), but never the "nos". So some girls just have what it takes. I accepted that my daughter didn't have it (she is quite grumpy, unfortunately and not really very self confident) and moved on. She got in later on when academics became more important.
So, please don't take it so badly. It is very tough, I know ( believe me I do) but your daughter must have some form of shyness/lack of confidence.
Refusing to do the task is unfortunately a big no-no.
Is she in a school that will prepare her for the 7 + now? That is where you will see if she is academic enough for those schools. Remember, for a child who struggles those schools are a nightmare.
So, relax now and try to prepare her without pushing her too hard.
I really hope this helps.