FB like button is not displayed in every pages

Friends,

I can't see FB like button even there's a code for it already on the source
"fb:like"

<fb:like href="http://www.facebook.com/stevesommerfeld/node/502" colorscheme="light" font="verdana" action="like" width="350" show_faces="true" layout="standard" send="false"></fb:like>

Am I missing something here ?

Any sugestions will be very appreciated,
Thanks