Custom Comment Form

I am using the GD Star Ratings plugin to turn my comments into "reviews".

When I try to modify the Comments Plus plugin to display the star rating entry, I am running into trouble.

This:

function _prepare_twitter_comments () {

		if (!$this->model->current_user_logged_in('twitter')) return $this->_prepare_twitter_login();
		return "
			<p>" . __('Connected as', 'wdcp') . " <b class='connected-as'>" . $this->model->current_user_name('twitter') . "</b>. <a class='comment-provider-logout' href='#'>Disconnect</a></p>
		";
if (defined("STARRATING_INSTALLED")){
echo '<p><label for="url">Your Rating:</label>';
wp_gdsr_comment_integrate_standard_rating();
echo '</p>';
}
if (!$this->model->current_user_logged_in('twitter')) return $this->_prepare_twitter_login();
		return "
			<textarea id='twitter-comment' rows='8' cols='45' rows='6'></textarea>
			<p><label for='post-on-twitter'><input type='checkbox' id='post-on-twitter' value='1' checked='checked' /> " . __("Post my review on Twitter", "wdcp"). "</label></p>
			<p><a class='button' href='#' id='send-twitter-comment'>" . sprintf(__('Review via %s', 'wdcp'), 'Twitter') . "</a></p>
		";
	}

... refuses to display anything past the if(defined(StarRating) line.

What should I change?