I'm using Google Analytics trying to type my own variables and using their types package as a dev dependency. They declare global variables in their types package like so:

declare var gaClassic: GoogleAnalytics;
declare var ga: UniversalAnalytics.ga;
declare var _gaq: GoogleAnalyticsCode;
declare var _gat: GoogleAnalyticsTracker;

When I go to try to use it in an interface it says it cannot find it, but the IDE still picks up the namespace, why is this?