Facebook Like button keeps disappearing

I've inserted this code into each of the pages of the site I'm working (http://killerstuffandtonsofmoney.com/) on to add a facebook like button.

The code looks like this:

<div style="text-align: center;"><div id="fb-root"></div><script src="http://connect.facebook.net/en_US/all.js#xfbml=1"></script><fb:like href="http://killerstuffandtonsofmoney.com/" send="false" width="290" show_faces="false" colorscheme="dark" font="arial"></fb:like></div>

It works fine until I edit and update the page again to add content, etc.

Then the code changes to this:

<div style="text-align: center;">

<script src="http://connect.facebook.net/en_US/all.js#xfbml=1"></script>
</div>

And the facebook like button disappears.

Why is this?