intellisense.undefinedWithCompletionsOf(value) not showing intellisense options for provided value

I want to use the function 

intellisense.undefinedWithCompletionsOf(value)

to show intellisense for window for all undefined values. But I cannot get it to work. For now, I have 2 files: "intellisenseCode.js" which has:

intellisense.undefinedWithCompletionsOf(window);

and "appCode.js" which has:

/// <reference path="intellisenseCode.js" />

var hello;
hello. // should show intellisense for window object here

Am I doing something wrong here? 

Thanks!