undoubtably a very pretty shot. it's sitting on the cusp about whether or not it meets the challenge; from the rays of light it's clear shadows are being cast, it's just you don't get to see any of them (i personally don't think silhuoettes are the same thing). it is a fantastic sky though, and the detail of the trees outline is nicely captured. i wonder if you tried shooting closer to the trees and with your back to the sun... 6.
i'm starting to see the beginning of the tree shadows right by the sun and i'm left wondering if something prevented you from just capturing the base of the trees with the sun a few degrees higher. I bet that would have been a very interesting image and been more in line with what i believe voters are looking for.