Replacing Header Text With Header Image

Hello all,

I have a fairly simple problem (I think) – I have changed my header code so that I have a header image instead of text title. As far as I can tell there is nothing wrong with the code, but the image still does not appear on my site. I have pasted the code below:

<div class="head">
					<div class="logo">
<h1 class="site-title"><a href="<?php echo home_url( '/' ); ?>" title="<?php echo esc_attr( get_bloginfo( 'name', 'display' ) ); ?>" rel="home"><img src="<?php bloginfo('stylesheet_directory');?>/images/logo.png"/></a></h1>

As you can see on my site the image just appears as a broken image (http://giftersguidetothegalaxy.com/).

If someone could have a quick look it would be greatly appreciated. I am pretty sure I am just missing something small, but all feedback is appreciated.

Thanks!