Rails - Jun 2006 - struggling with relatively simple out of model updating

I''m trying to do a In/Out thing...

In my in_outs_controller.rb

  def edit_in_out
    @in_out = InOut.new
    @in_out.user_id = params[:id]
    @user = User.find_by_id(@in_out.user_id)
    if @in_out.save
      @user.update_attribute(:in_out, params[:user][:in_out])
      flash[:notice] = ''In/Out was successfully updated.''
      redirect_to :action => ''list''
    else
      render :action => ''edit_io''
    end
  end

The error I get is...
ActiveRecord::AssociationTypeMismatch 
InOut expected, got String

Request
Parameters: {"user"=>{"will_return"=>"",
"in_out"=>"In"}, "commit"=>"
Save ", "id"=>"19"}

Users table has
    add_column :users, :in_out, :string, :limit => 3
    add_column :users, :will_return, :string, :limit => 48

How can I do this?

Craig