diff --git a/app/helpers/courses_helper.rb b/app/helpers/courses_helper.rb
index 4b6a84b57..b4b89bb0f 100644
--- a/app/helpers/courses_helper.rb
+++ b/app/helpers/courses_helper.rb
@@ -343,6 +343,9 @@ module CoursesHelper
   #获取作业的互评得分
   def student_score_for_homework homework
     member = searchTeacherAndAssistant(homework.bid.courses.first).first#searchPeopleByRoles(homework.bid.courses.first,TeacherRoles).first
+    if member.nil?
+      return "0.00"
+    end
     student_stars = homework.rates(:quality).where("rater_id <> #{member.user_id}").select("stars")
     student_stars_count = 0
     student_stars.each do |star|
@@ -354,6 +357,9 @@ module CoursesHelper
   #获取作业的教师评分
   def teacher_score_for_homework homework
     member = searchTeacherAndAssistant(homework.bid.courses.first).first#searchPeopleByRoles(homework.bid.courses.first,TeacherRoles).first
+    if member.nil?
+      return "0.00"
+    end
     teacher_stars = homework.rates(:quality).where("rater_id = #{member.user_id}").select("stars").first
     return format("%.2f",teacher_stars == nil ? 0 : teacher_stars.stars)
   end
diff --git a/db/schema.rb b/db/schema.rb
index 72d49adf4..26c82491d 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -11,7 +11,7 @@
 #
 # It's strongly recommended to check this file into your version control system.
 
-ActiveRecord::Schema.define(:version => 20140704034832) do
+ActiveRecord::Schema.define(:version => 20140708023356) do
 
   create_table "activities", :force => true do |t|
     t.integer "act_id",   :null => false