Object [object Object] has no method 'normalize' when trying to create animation

I'm trying to create a flight path animation similar to the Camera example in the Sandcastle demo (http://cesium.agi.com/Cesium/Apps/Sandcastle/index.html?src=Camera.html). Here's the code in question:

var destination = Cesium.Cartographic.fromDegrees(self.longitude, self.latitude, 15000.0);
var animation = Cesium.CameraFlightPath.createAnimation(scene.getFrameState(), {
  destination: destination

However, when on the call to createAnimation I get the following error on line 73592: var dot = start.normalize().dot(end.normalize());

end.normalize is not a function

createAnimation expects destination to be a Cartesian3. Use createAnimationCartographic instead.

Ugh, I feel stupid. Thanks!