problem with loss of css when upgrading to version 3.6

Thanks for the new version. I'm using WP 3.0.4

I had a problem that my site lost all it's css layout when I upgraded. In the source code from the web browser I could see this:

<link rel="stylesheet" href="/?bfa_ata_file=css" type="text/css" media="all" />

Looking at the header.php file I can see that version 3.6 shows:

<link rel="stylesheet" href="<?php echo $homeURL; ?>/?bfa_ata_file=css" type="text/css" media="all" />

where as in 3.5 the code was

<link rel="stylesheet" href="<?php bloginfo('url'); ?>/?bfa_ata_file=css" type="text/css" media="all" />

not sure why $homeURL; hasn't worked.

John