I think your missing a . in front of the html$ so try this:

RewriteEngine On
RewriteRule ^.*L([0-9]+).*\.html$ /Detailed/$1.html [L]


If you LinksSQL install isn't building pages in the root directory you'll need to change it to something like this:

RewriteEngine On
RewriteRule ^.*L([0-9]+).*\.html$ /links/Detailed/$1.html [L]

For example, if the full url to your Detailed pages looks like this: http://www.yourdomain.com/links/Detailed/52.html

Third, you may want to make sure your using the right rewrite global.

If that doesn't work you better try make sure mod_rewrite is even turned on.

Hope that helps!

Jonze