Hello,
I can’t really tell from your URLs since the Twitter Cards markup is empty, but since you mentioned the Cards were displaying properly when opening the Tweets, I think you markup must be correct on the page that you shared on Twitter.
Please keep in mind that the Photo Cards are not expanded in the Timeline, only pictures uploaded on Twitter and Vines are currently expanded in the Timeline, which should explain what you observed.
Please let us know if you have any further questions.