my bad.

app/controllers/presentation_questions_controller.rb

@@ -2,17 +2,16 @@ class PresentationQuestionsController < ApplicationController
   before_filter :check_authorization, :load_presentation
 
   def create
-    @question = @presentation.presentation_questions.new(params[:presentation_question]) do |q|
-    @question.user = current_user
+    @question = @presentation.presentation_questions.new(params[:presentation_question])
+    @question.user = @current_user
     if @question.save
       redirect_to :action => "show", :controller => "presentations", :id => params[:presentation_id]
     else
       render :action => "show"
     end
   end
-
-  private
-    def load_presentation
-      @presentation = Presentation.find(params[:presentation_id])
-    end
+
+  def load_presentation
+    @presentation = Presentation.find_by_id params[:presentation_id]
+  end
 end