Sencha Touch - Map.Geo = null

I am trying to follow this simple tutorial on Sencha Touch http://dev.sencha.com/deploy/touch开发者_开发百科/getting-started.html

I keep getting the JavaScript error: Uncaught TypeError: Cannot call method 'on' of null

This relates to the Map.geo property which is not getting set correctly. I am using the eact same code as on the link. I have tried putting on another box, in case it was a firewall issue, but get the same error.

In your Application JavaScript File, replace getLocation:true with useCurrentLocation:true.