Like Rap said, none of us can have any official answers...
I've gone through seminary and i can't either. but i can tell you what' i've heard.
sometimes ppl have to really believe (and want) to be healed. This is not to say that the woman doesn't. But sometimes we don't know that, or don't know if we have enough... or some part withus sabotages our efforts.

If she is a "wounded healer" then maybe she takes in other's pain in order to heal them...

Some would say "God can only do for us what he can do through us".

Some might say it is Karma.

My Dean would have said "it just is". That God is the only power and yet not the cause of things. That is to say that even tho (this is her belief) there is no such thing as evil, and that there is only one power, that that power does not dictate the deeds in the world or our own life... not that they are separate, but that they just "are". and it is good. That there is inherent good in things (which is different than to say things "are" good as in "we like them"). She also used to say "G.O.D = Good Orderly Direction"

There are so many possibilities. You must believe what is right for you (but personally, I always think questioning is good).

Have i confused you yet? =) Kiya