Cannot create assoication between new objects for nested model form in rails

I am watching on railscasts and tried to write the example with my own
hands. But I got an trouble with the step of: Creating The Form.

It requires creating association between Survey and Question. But this
association cannot be established in my rails application so no questions
appear in the form

For more details, please see my post on the stackoverflow

If you want answers here it is generally best to ask the question
here. Most will not be bothered with following the stackoverflow
link. As a general point it is considered bad practice to cross post
to multiple places at the same time. Ask on one and if the problem is
not solved then ask somewhere else, but not both at the same time.
For all we know your question has already been solved somewhere else
that you have asked and we are wasting our time.