Nope, you're correct, it's Alison Krause:

I DON'T KNOW WHY
(Alison Krause)

I don't know why the sky is so blue
I don't know why I'm so in love with you
If there were no music, I would not get through
I don't know why I know these things, but I do

I don't know why somewhere dreams come true
I don't know where we'll find a place for you
Every time you look that way I lay down my life for you
I don't know why I know these things, but I do

I don't know why sun can make you cry
I don't know how I'm bound to get you back, but I'll try
They don't mean to cause you pain, they're just afraid of loving you
I don't know why I know these things, but I do

I don't know why the trees grow so tall
I don't know why I don't know anything at all
If there were no music, I would not get through
I don't know why I know these things, but I do, I do
I don't know why I know these things, but I do