Custom markers

Hi; i did add that code:

/**
 * Filter snippet
 */
function prefix_pronamic_google_maps_marker_options_icon( $url ) {
	switch ( get_post_type() ) {
		case 'my_type':
			return 'http://google-maps-icons.googlecode.com/files/seniorsite.png';
		case 'my_other_type':
			return 'http://google-maps-icons.googlecode.com/files/university.png';
	}

	return $url;
}

add_filter( 'pronamic_google_maps_marker_options_icon', 'prefix_pronamic_google_maps_marker_options_icon' );

to my functions.php but it dsn’t working. I was tryig with my own icon as well but nothing helps…Can somebody please help me?

http://wordpress.org/extend/plugins/pronamic-google-maps/