Twittercard unable to render card preview


#1

my website is: [sadat.pk][1] and i am using these meta tags

<meta property="twitter:card" content="summary" />
<meta property="twitter:title" content="Graphic Designer Portfolio" />
<meta property="twitter:description" content="I'm a visual artist based in lahore. i love creating beautiful, simple and effective designs" />
<meta property="twitter:site" content="@sadatmirxa" />
<meta property="twitter:creator" content="@sadatmirxa" />
<meta property="twitter:url" content="http://sadat.pk/" />
<meta property="twitter:image" content="http://sadat.pk/images/tweecard.png" />

when i go to validator link and put my link it says: ERROR: Internal server error

what is wrong?
[1]: http://sadat.pk