Mod Rewrite Help

[fluiduk]

Hi
Having some problems with the following code, any ideas why it would give me a 404

Options +FollowSymLinks
RewriteEngine On
RewriteBase /
RewriteRule ^property_news/([A-Za-z0-9-]+)/?$ /property_news/show_news.php?url_rewrite=$1 [L]

Thanks
Aaron