facebook write on someone’s wall

Why can’t I write on someone’s wall on facebook?
I’ve got a friend on facebook, who’s actually my sister, but I can’t write on her wall. I can’t even comment on pictures, or comment on anything, even after someone has written something first. Does this mean that she’s blocked me, or that there’s something wrong with facebook. I am allowed to send her messages, just not write on her wall. I’m assuming that she’s blocked me because this has been going on for quite some time now.
she may have you set to view her limited profile or she may have disabled her wall.
you can still send her messages. look for an “add as friend” or “remove friend” link.. that will tell you if she’s removed you from her list.
The Young Dads – Satan Wants You To Do Bad Things