Parenting 'Tweens (9-12) Support Group
This community is focused on the joys, challenges and concerns faced by parents of tweens (9 to 11 year olds). The major areas of child development include: physical development, perception and sensory development, communication and language development, cognitive development, emotional development and social development.
My son is almost 11 and he displays a similar attitude on occasion. I know I have to spend some serious one on one with him and we have to laugh and play together to break down those walls. That's when I make it really clear that he must treat everyone in the house with respect. Have a cheerful disposition, show kindness and be all around bearable to live with. We are all entitled to live with others that are not a nuisance or rude.
I found a speaker/therapist that deals with child raising pretty cut and dry...DrRay.com (Dr. Ray Guarendi) he's been around for a while and gave me a shot in the arm for parenting. I think as parents (especially as older parents) we get worn out at times and let them get away with too much, then we have some back tracking to do. Ug. All the best to you.
I don't know if this has any relevance to your situation, but it is one possibility. If even only one time you did not really hear what she was saying, or did something she thinks betrayed her trust, she could close up and it can be a challenge to get that door open again.