Index: src/wp-trackback.php
===================================================================
--- src/wp-trackback.php	(Revision 38779)
+++ src/wp-trackback.php	(Arbeitskopie)
@@ -112,9 +112,15 @@
 
 	$commentdata = compact('comment_post_ID', 'comment_author', 'comment_author_email', 'comment_author_url', 'comment_content', 'comment_type');
 
-	wp_new_comment($commentdata);
-	$trackback_id = $wpdb->insert_id;
+	$trackback_id = wp_new_comment( $commentdata, true );
+	if ( is_wp_error( $trackback_id ) )  {
+		trackback_response( 1, $trackback_id->get_error_message() );
+	}
 
+	if ( ! $trackback_id ) {
+		trackback_response( 1, __( 'Unknown error occured.' ) );
+	}
+
 	/**
 	 * Fires after a trackback is added to a post.
 	 *