up until now I used Feedburner to post my RSS feed to my Twitter account. Twitter cards worked without problem. e.g.: https://twitter.com/free_book_promo/status/297715976122806272
I disabled Feedburners feature and tweet now directly via the API. The problem is that Twitter Cards stopped working and I don’t know why?
e.g. this tweet should display Twitter photo card but it doesn’t: https://twitter.com/free_book_promo/status/297818717289603072