.htaccess problem

I am using WordPress in a subdirectory. After installing the fgallery plugin and setting it to use nice URLs, here’s my .htaccess file in the /public_html/wordpress directory:

# BEGIN FGALLERY
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteRule ^photos/?([^/]*)?/?([^/]*)?/?([^/]*)?/?([^/]*)?/?$   /wordpress/wp-content/plugins/fgallery/fim_photos.php?$1=$2&$3=$4 [QSA,L]
</IfModule>
# END FGALLERY
# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /wordpress/
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /wordpress/index.php [L]
</IfModule>

# END WordPress

The problem I face now is that all fgallery pages (example) give 404 errors in wget/W3 Validators/Google Webmaster Tools, despite working perfectly in browsers.

Any ideas about what’s preventing these tools from seeing the page?