acts_as_nested_set in lib

Hi everyone,

I have a model called category that uses acts_as_nested_set so I can use
parent/child functionality. It seems to work fine when I call
Category.children.each in the category controller/view, but I'm trying
to work on a rake task that needs to loop through all of the
however I just keep getting an error saying

undefined method `childen' for #<Array:0xc26c748>

I'm thinking I somehow need to include the acts_as_nested_set in the
rake file but I'm not sure how?

Thanks in advance,