Problem with session

Hi, I have problem when i tried to logging logging successfull, but when tried to find out the current cuser details by session it always says nil

code for loging:-

@user = User.new(params[:user])     #session[:user_id] = nil

    case request.method     when :post

      respond_to do |format|         if @current_user = User.authenticate(@user.email, params[:user] [:hashed_password])           session[:user_id] = @current_user.id           flash[:notice] = "user login successfully !!!"           format.html { redirect_to(users_path) }         else           flash[:notice] = " better try next time !!!"           format.html { render :action => "index" }         end

i want to fetch user details from user table by from user controller Couldn't find User with ID=2

but the current user id is not 2, it always take id 2 code:- @user=User.find(session[:user_id])

Thank's ajit