paginate_by_sql throwing error

Trying to use paginate_by_sql and am getting an error. I have followed the example in finder.rb and have put the following in my controller:

def list
@contacts = Contact.paginate_by_sql ['SELECT * FROM contacts WHERE customer_id = ?', 2],
:per_page => 2, :page => params[:page], :total_entries => 3,
:order => 'name'
end

but whenever I try to view the page I get the following error:

DBI::DatabaseError in ContactsController#list

Not enough SQL parameters

I have attached the full error.