Image in a Tumblr theme does not display in Firefox

My friend asked me to add a header image advert to his Tumblr blog, http://proudlockstyle.com. (I did not make the theme)

I went into the theme editor and added the necessary html just inside the main container:

<div style="text-align:center;">
    <a href="http://www.reiss.com/">
        <img src="http://static.tumblr.com/1gdukju/Qrtmei9p1/all_banners_mens1_468x60.jpg" />
    </a>    
</div>

This worked fine in Chrome, Safari and even IE! But the image does not show when the site is viewed in Firefox. When I inspect it in Firebug the <img> tag is grayed out.

Can anyone identify why the image isn't showing?

Solution

You're running adblock in your Firefox right? Change the name drop the banners bit. It doesn't show in my Chrome either unless I disable adblock