It’s probably me! I spent the day adding the correct meta tags. The Twitter card validation tool says everything is OK and that *.esl-lounge.com is approved.
Here’s a tweet that should be showing a card: https://twitter.com/ESLLounge/status/398915414740045825
code:
<META property="og:title" name="twitter:title" content="Cambridge First Certificate in English Examination - Free Test Prep Materials | ESL Lounge" />
<META NAME="description" CONTENT="Free test preparation materials for Cambridge FCE First Certificate in English examination. Materials for Use of English and Reading papers. 2008 revised exam.">
<META property="og:description" name="twitter:description" content="Free test preparation materials for Cambridge FCE First Certificate in English examination. Materials for Use of English and Reading papers. 2008 revised exam." />
<meta name="twitter:card" content="summary">
<meta name="twitter:site" content="@esllounge">
<meta name="twitter:creator" content="@esllounge">
<meta name="twitter:domain" content="http://www.esl-lounge.com/">