Mod RewriteRule not working on all URL's

Question

this is my .htaccess

Options +FollowSymLinks
RewriteRule ^(.*)wp-content/uploads/(.*) $1watermark.php?src=wp-content/uploads/$2

# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>

# END WordPress

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this line is my issue

RewriteRule ^(.*)wp-content/uploads/(.*) $1watermark.php?src=wp-content/uploads/$2

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all my images are in subfolders within wp-content/uploads. an example of http://darrenkynochphotography.co.uk/wp-content/uploads/2008/09/darrenprofile.jpg does what it should and redirects the image through a watermark script.

But this example http://darrenkynochphotography.co.uk/wp-content/uploads/2011/05/23-2-950x635.jpg doesnt work at all, along with any other images. I cant see where i am going wrong here at all as it should work

Answer 1

The RewriteEngine directive enables or disables the runtime rewriting engine. If it is set to off this module does no runtime processing at all.

...

Default: RewriteEngine off

Apache mod_rewrite documentation

If you have directives which appear before a RewriteEngine on directive, they will be ignored.