Map Icons stacking order

Issue Summary

I've created a view map for a client that uses a 12 item taxonomy to display 12 different icons on their map. The client would like the icons to "stack" in the taxonomy weight order. I thought that sorting on that taxonomies items weight might produce that result, but it doesn't. Sorting does not seem to have any effect on the stacking order of the icons. Which leads me to my question: What controls the stacking order of the icons. By stacking order I mean the loading order of the icons. Is there a way to control that loading order? The map can be viewed at: http://www.rnp.org/project_map.
Thanks in advance for your help