D3.js Collapsible Force Layout: Links are not being generated?

I'm trying to generate a collapsible force layout similar to this example: http://bl.ocks.org/mbostock/1062288: T...

D3 - Collapsible Force Layout modification?

First of all, I'm new to d3.js and I'm amazed with this and what it is possible to do. Saying that, sorry by my "noo...