[Plugin: Comprehensive Google Map Plugin] Geo Mashup not working

Have tried creating a GEO Mashup map several times on different pages within my site but it only ever shows up as a grey box with a black outline along with the following error message:

ATTENTION! (by Comprehensive Google Map Plugin)

Dear blog/website owner,
You did not specify any marker locations for the Google map! Please check the following when adding marker locations:
[a] In the shortcode builder, did you add location(s) and clicked the Add button before generating shortcode?
[b] In the widget, did you add location(s) and clicked Add button before clicking Save?

Please revisit and reconfigure your widget or shortcode configuration. The map requires at least one marker location to be added..

I have lots of maps on my site on various pages, all of which were created without any problems and all currently working. It is only the Geo Mashup that isn’t working, and doesn’t seem to be able to aggregate my other maps at all.

Any ideas?

http://wordpress.org/extend/plugins/comprehensive-google-map-plugin/