Set featured image using wp_insert_post

            // Auto post ( Unique File Date ).
            $postData = array(
                'post_category' => array( $Category ),
                'post_status' => $Post_Status,
                'post_type' => $Post_Type
            );
            $post_id = wp_insert_post( $postData );

            $getImageFile = 'http://localhost/Multisite/test2/wp-content/uploads/sites/4/Auto Post/twitter.png';

            $attach_id = wp_insert_attachment( $postData, $getImageFile, $post_id );
            require_once( ABSPATH . 'wp-admin/includes/image.php' );

            $attach_data = wp_generate_attachment_metadata( $attach_id, $getImageFile );

            wp_update_attachment_metadata( $attach_id, $attach_data );

            set_post_thumbnail( $post_id, $attach_id );

The code above make a post successfully but it is not setting the post featured image. I don't know what i am doing wrong here.