[Plugin: Pronamic Google Maps] Different icons in mashup

How can I display different icons on the mashup map based on the post category , or on custom fields?

I tried this, but does not work:

function prefix_pronamic_google_maps_marker_options_icon($url) {
$tipo = get_post_meta(get_the_ID(), 'franquiciado', false);
switch(get_post_meta(get_the_ID(), 'franquiciado', false)) {
case 'post':
$url = 'https://google-maps-icons.googlecode.com/files/seniorsite.png';
break;
case 'page':
$url = 'https://google-maps-icons.googlecode.com/files/university.png';
break;
}
return $url;
}
add_filter('pronamic_google_maps_marker_options_icon', 'prefix_pronamic_google_maps_marker_options_icon');

thanks.

https://www.ads-software.com/extend/plugins/pronamic-google-maps/