knockout viewmodel and requirejs - mvvm

Question

I have recently started to work with requirejs and when I try to create a simple viewmodel I get an strange exception. The exception comes from the knockout-2.1.0.js file and the exception is "Only subscribable things can act as dependencies".
define("PageViewModel", ["knockout-2.1.0"], function(ko) {
return function PageViewModel() {
var self = this;
self.visiblePage = ko.observable("StartPage");
self.showPage = function (pageName) {
self.visiblePage(pageName);
};
};
});
As you can see the viewmodel is extremly simple and since the error is in the knockout js file, it seems like requirejs is working as it should. I have been looking at: http://knockoutjs.com/documentation/amd-loading.html
The exception occur when coming to the line: self.visiblePage = ko.observable("StartPage");
Any ideas on what I'm doing wrong?
Thanks,
Ludwig
Update:
This is the module containing the pageviewmodel:
define("ViewModelFactory", ["StorageService", "PageViewModel", "AddUnitViewModel", "AddRoomViewModel"],
function (StorageService, PageViewModel, AddUnitViewModel, AddRoomViewModel) {
//var repositoryStorage = new StorageService();
var createAddRoomVM = function () {
var vm = new AddRoomViewModel();
vm.setRepository = StorageService.getRoomRepository();
return vm;
};
var createAddUnitVM = function () {
var vm = new AddUnitViewModel();
vm.setRepository = StorageService.getUnitRepository();
return vm;
};
var createPageVM = function () {
var vm = new PageViewModel();
return vm;
};
return {
createPageVM:createPageVM,
createAddRoomVM: createAddRoomVM,
createAddUnitVM: createAddUnitVM
};
});
And the module calling the factory
define("ApplicationViewModel", ["ViewModelFactory"],
function (viewModelFactory) {
mainVM = null;
var initVM = function () {
mainVM = {
page: viewModelFactory.createPageVM(),
addRoom: viewModelFactory.createAddRoomVM(),
addUnit: viewModelFactory.createAddUnitVM()
};
};
var getVM = function (viewName) {
switch (viewName) {
case "AddRoom":
return mainVM.addRoom;
case "AddUnit":
return mainVM.addUnit;
default:
return null;
}
};
var getPageVM = function () {
return mainVM.page;
};
return {
initVM: initVM,
getVM: getVM,
getPageVM: getPageVM,
mainVM: mainVM
};
});
And the class containing the applicationViewModel:
define("Bootstrapper", ["knockout-2.1.0", "Routing", "ApplicationViewModel"],
function (ko, routing, applicationViewModel) {
var run = function () {
applicationViewModel.initVM(); <-- after here mainVM.page is null
var mainVM = applicationViewModel.mainVM;
routing.initRouting(applicationViewModel);
ko.applyBindings(mainVM);
routing.showView("StartPage");
alert("Start");
};
return {
run: run
};
})

Answer 1

Your problem may have been caused by Knockout 2.1, which didn't work well when ko was not a global variable.
Knockout 2.2 should work fine, and I see from your comment this did indeed fix the problem.