Module development: Invalid method createView

I've been searching for the past few hours and I cannot figure this out. I'm creating a titanium module for iOS in Obj-C. The module compiles fine. My test project can see the module, however, I keep getting this error:

Invalid method (createView) passed to TiVolumesliderModule at app.js

My app.js contains

var VolumeSlider = require('ti.volumeslider'); //-- this works
Titanium.API.info("module is => "+VolumeSlider); //-- this works: module is => [object TiVolumesliderModule]
 
var volumeSlider = VolumeSlider.createView({
  width: '90%',
  height: 'auto',
  color: '#000',
  bottom: 10,
});