Some page url doesn't show up twitter card in tweet


#1

http://www.bitben.org/articles/version-control-for-website-via-ftp-with-bazaar/ - Displays twitter card
http://www.bitben.org/articles/awesome-101-vim-commands/ - Doesn’t Displays twitter card

Both urls are of my site, one is display the twitter card, but the other one (some urls doesn’t display summary in the tweet) . All these urls share same twitter card properties. Why is it happening like this?

I have already tweeted this here http://twitter.com/bensonshaji

Can someone help me?