Alloy.createController() error

Hi all,

Having an unusual problem with creating a controller. The code I modeled it from works fine. Using the following:

• Ti SDK 3.1.2
• ios 7.x simulator
• mobile app
• Mac OS X Mavericks
• Titanium Studio, build: 3.1.3.201309132423

Things I've tried with no success:

• clean/rebuild project
• comment out open() call in target file and rewrote controller call as controller.getView().open();
• compared my code with solutions found in this forums
• ensured I have appropriate controller and view files.

In my index.js file, I pop an alert on a Register button to allow the user to choose to register as either a user or vendor. That works fine. The problem occurs after an option is clicked. Here's the code:

var helper = require('helpers');
 
$.registerButton.addEventListener('click', function(e) {
 
    var popup = helper.showDialog({
        cancel : 2,
        title : "Registration",
        message : "Register new?",
        buttonNames : ['User', 'Vendor', 'Cancel']
    });
    popup.addEventListener('click', function(e) {
 
        //If user does not press Cancel, then navigate to appropriate register page.
 
        if (e.index !== 2) {
            if (e.index === 0) {
                var controller = Alloy.createController('registerUser');
                controller.getView();
            } else {
                var controller = Alloy.createController('registerVendor');
                controller.getView();
            }
        }
    });
});
 
$.index.open();

I open the selected controller in their respective .js files. When I choose User or Vendor button (in this case, User), I get the dreaded Red Screen of Death. The message undefined is not a function (evaluating $.registerUser.open()) at registerUser.js (line 52).

Line 52 = $.registerUser.open();

No big surprise there. That's the only command in the registerUser.js file. What am I missing here? Hope I've provided enough detail. If not, please ask.