smart backgrounds

I have renamed my folders to the correct default name
I have put everything in the right place
and i have named the images correctly and also made sure the css was edited to match the image names.
and placed a transparent gif in the header.php file like so:
define('HEADER_LOGO_IMAGE', 'trans-image.gif');

The smart background is still not working!

here is the link to my site:
http://blueamigo.co.uk/zencart/

you will see that the transparent gif is creating a white space in the logo wrapper

any ideas!

thanks

Glen