0 visitors online since installation

Hi There

Seems I have a similar problem to the one here:
http://wordpress.org/support/topic/my-visitor-map-is-stuck-on-0-help?replies=2

But I thought it was better to create a new thread.

I am hosting 3 sites on the same server and all 3 have Visitor maps installed. However on 1 of the 3, Visitor Maps plugin has never worked. It’s been up for a long time now but has never had a single visitor according to Visitor Maps. Even when I test from different locations.

Ive checked header.php as per the other thread and it does contain: ‘<?php wp_head(); ?>’

Do you have any suggestions on how to troubleshoot?

Thank you

http://wordpress.org/extend/plugins/visitor-maps/