Problem with Sortable Table Columns

Hey everybody,
i've got a really nerving problem with sorting table columns, which i
cant solve by myself. So i need your help.

I follwed all steps as showed in this railscast:
http://railscasts.com/episodes/228-sortable-table-columns

and it worked very well.

BUT as i restated my app i get this stupid error message:

NoMethodError in GroupsController#index

You have a nil object when you didn't expect it!
You might have expected an instance of Array.
The error occurred while evaluating nil.+

RAILS_ROOT: c:/Users/Vennil/rails/gruppenmanager
Application Trace | Framework Trace | Full Trace

c:/Users/Vennil/rails/gruppenmanager/app/controllers/groups_controller.rb:12:in
`index'

Why the hell does it worked before and not now? Any ideas?

Many thanks in advance!

Ray

12| @users = User.find(:all, :order => sort_column + " " +
sort_direction)

Well, which value is null, sort_column or sort_direction?

Oftentimes, I've seen code that sets the direction for descending, but
not ascending, which might be your issue.