Wordpress - Why are the comments disabled by default on my custom_post_types?

Ok - so I solved this. Here is what appears to be the problem.

Comments are disabled by default for custom-post-types. This happens even if you have them enabled in the overall settings

To fix it, all I had to do was the following:

1. In SETTINGS > DISCUSSION uncheck the "Allow people to post comments on new articles" setting.
2. Click "Save Changes"
3. Now go back and re-check "Allow people to post comments on new articles"
4. Click "Save Changes"

It seems that for custom post types you need to kind of kick-start this setting. All new posts for created custom-post-types will have the box enabled by default. Existing posts will retain their previous setting. I'm assuming it's the same for allowing trackbacks. Hopefully this helps someone...

This is the default state.. you need to change the "Supports line" where you build your custom post type..

Meaning this line:

// or something similer that starts the same

'supports' => array('title','editor','author','excerpt','revisions'),

To this line:

'supports' => array('title','editor','author','excerpt','comments','revisions'),

Hope this helps.
Cheers, Sagive.

ADDED FUNCTION (INSIDE FUNCTIONS FILE):

function default_comments_on( $data ) {
    if( $data['post_type'] == 'your_custom_post_name' ) {
        $data['comment_status'] = 1;
    }

    return $data;
}
add_filter( 'wp_insert_post_data', 'default_comments_on' );

None of the following suggestions worked for me. Sagive SEO's function almost worked for me. I checked my database to find that the only values for comment_status are open and closed. That function inserted 1 as a value. I revised the function and it seems to work perfect now. I hope this helps someone.

function default_comments_on( $data ) {
    if( $data['post_type'] == 'your_custom_post_type_name' ) {
        $data['comment_status'] = 'open';
    }

    return $data;
}
add_filter( 'wp_insert_post_data', 'default_comments_on' );