Dynamically populating a drop-down custom field

I've snagged some code from this forum that helps me dynamically populate a category of posts into a drop down menu.

However, If i try to use a custom field drop down menu instead of a regular drop down menu (using same specifications), the drop down will not dynamically populate.

/* Dynamic drop-down on /register
------------------------------------------------------ */
add_filter('gform_pre_render_1', 'populate_posts');
function populate_posts($form){
    foreach($form['fields'] as &$field){
        if($field['type'] != 'select' || strpos($field['cssClass'], 'populate-posts') === false)
            continue;
        $posts = get_posts('numberposts=-1&post_status=publish&category_name=members');
        $choices = array(array('text' => 'Select a member company', 'value' => ' '));
        foreach($posts as $post){
            $choices[] = array('text' => $post->post_title, 'value' => $post->post_title);
        }
        $field['choices'] = $choices;
    }
    return $form;
}

Any ideas on what I can do differently with this script to ensure I can dynamically populate a custom field (drop down) ?

Hi, I'm having the same problem. I can get a typical drop-down field to populate with a custom post type, but not the custom-field drop down - it just won't populate. Please help, as this is how Wordpress can really be used like a relational database, by populating custom fields with ID's of custom post types.

That worked! Great. Thank you.