Display all Post Types

We are trying to display all posts and custom post types in the slider. Right now the slider is only displaying standard wordpress posts.

We are using short codes in the php template files, and the posts are being displayed depending on the category.

[promoslider post_type="post" category="homepage-featured-slider" display_nav="links" width="100%" display_title="default" numberposts="5"]

How can we display ALL post types that are in this category?

Thanks!

http://wordpress.org/extend/plugins/promotion-slider/