functions prefix breaks plugin

Hi,

I just found this plugin and i really like it so far. While testing the plugin on a basic WordPress environment i tried to add a prefix as explained in the FAQ.

When i add the following code to my functions.php:

add_filter( 'cpsh_prefix', 'set_shortcode_prefix' );
function set_shortcode_prefix() {
    return 'myprefix_'; // edit this part if needed
}

The whole plugin stops working and shortcodes show as real text.

See screenshot for problem: http://oi39.tinypic.com/9rk86a.jpg

Whats wrong? Please help!

Niels

http://wordpress.org/plugins/column-shortcodes/