Have you tried creating your busy indicator object globally rather than inside this specific function (I also don't understand the scope of this "initialize" function... I assume this is app-specific code).
In your app's .js file (yourProject\apps\yourApp\common\yourApp.js) do something like this:
var busy;
function wlCommonInit() {
busy = new WL.BusyIndicator();
Then, in your initialize()
function, call busy.show()
and busy.hide()
when required.