Google maps displaying on back side, but grey on events page

I’ve installed the most recent version of the plugin. The google maps for Events/Locations appear correctly when editing events/locations. But on the actual events page (front side), they appear as grey (no map shown).

I’m running WP 3.5.1 on Nimble Theme.

I’ve already tried disabling other plugins — no change.

Here’s a sample page on the front side: http://66.7.206.71/~albare/cms/events/ilott-theatre-wellington-new-zealand/

Any idea why this would be happening?

http://wordpress.org/extend/plugins/events-manager/