Reading "created_at" from XML

I'm having trouble printing the "created_at" from the parent application (I'm using ActiveResource).

I noticed the XML document replaces all underscores with dashes (i.e. created_at is transformed to created-at).

Other data -- like post.title, post.body, -- print out fine; only post.created_at doesn't.

Any idea on how to correctly print out post.created_at from the XML?