Q: Song purchased but wont download. Shows up grey when I click show entire album.

I downloaded the Avicci levels remix album. The skrillex song shows up unplayable and in grey font. As if it wasn't purchased. However, when I go on intunes the song appears as if I have purchased it. Which it should, as I bought the entire album and not individual songs. I can't find the song anywhere in my library or downloads. Where has it gone and how can I find it??