RSS - 显示图像，而不是机箱？

I have made a rss feed for my website, but right now the feed is not really displaying a image but just a link to the image as a enclosure. I would like to know what changes I need to make so I can actually display a image in the rss feed.

echo '  
   <item>  
      <title>'.html_entity_decode($gag[story], ENT_COMPAT, "UTF-8").' - '.$thesitename.'</title>  
      <description><![CDATA['.html_entity_decode($gag[story], ENT_COMPAT, "UTF-8").']]></description>  
      <link>'.$thebaseurl.'/post/'.$gag[PID].'</link>  
      <guid>'.$thebaseurl.'/post/'.$gag[PID].'/</guid>';
      if($gag[pic] != ""){echo '
      <enclosure type="image/jpeg" url="'.$thebaseurl.'/pdata/t/'.$gag[pic].'" length="1" />';


      }
echo  '