Search form for custom post type with pretty permalinks

Hi,

I’m having trouble creating a custom search form for my custom post type. The custom post type is ‘products’.

I have singled down the default search so that it only searches the post type ‘post’.

However, when I try to create my custom search form for my products post type, it only works when I’m on default permalinks. When I go into custom permalinks like

/%category%/%postname%/

it defaults my search back to the default one, and therefore doesn’t show me my custom post type.

What I have put in my custom search form to search custom post types, is

<input type="hidden" value="products" name="post_type">

I hope that makes sense.