Custom logo only shows up when logged in (SOLVED)

I've just installed Gallery2 in a sub-directory of my site, and created a custom logo (250 x 107). I edited the theme template (Matrix) to display this logo with a custom link (my site's home page). It works just fine as long as I am logged in, both in admin and guest view. As soon as I log out however, the logo shrinks to the default size (107 x 87), and the link reverts to the gallery home page (main.php).

I would like to link to main.php from my site and let visitors view the album without any sort of login, so I need the custom logo and link to work without login. I'm new to Gallery2, so I might be doing something really stupid. What am I missing here?

Thanks in advance for your help.

Edit: Never mind. I can't pretend to understand why, but temporarily selecting a different theme and then coming back to Matrix has fixed the problem. It's odd, because I had cleared both the template and browser cache earlier without success. Whatever it was that pushed my changes through now, I'm glad it's working. Thanks anyway.