What's the problem with paginate?

I'm new in rails, but it attracts me so much. When i learn "Agile Web
Development with Rails, 2nd Edition", i find that 'pagniate' is very
useful.
But when i try to make a sample by myself, the pagniate seems
uneffective. No matter what the param 'page' is, it will only list the
first page items.
My source code is as simple as
1 def list
2 @agent_relationship_pages, @agent_relationships =
paginate :agent_relationships, :per_page => 4
3 end
If i change line 2 to
2 @agent_relationship_pages, @agent_relationships =
paginate :agent_relationships, :per_page => 4, :page => params[:page]

error page comes, and shows "Unknown options: page"

What happens?