diff --git a/app/controllers/courses_controller.rb b/app/controllers/courses_controller.rb
index c54a419cb..b4be3deb7 100644
--- a/app/controllers/courses_controller.rb
+++ b/app/controllers/courses_controller.rb
@@ -25,25 +25,28 @@ class CoursesController < ApplicationController
 
   def join
     if User.current.logged?
-      course = Course.find(params[:object_id])
-      unless User.current.member_of_course? course
-        if params[:course_password] == course.password
-          members = []
-          members << Member.new(:role_ids => [10], :user_id => User.current.id)
-          course.members << members
-          StudentsForCourse.create(:student_id => User.current.id, :course_id => params[:object_id])
-          @state = 0
+      course = Course.find_by_id params[:object_id]
+      if course
+        @state = 4
+      else
+        unless User.current.member_of_course? course
+          if params[:course_password] == course.password
+            members = []
+            members << Member.new(:role_ids => [10], :user_id => User.current.id)
+            course.members << members
+            StudentsForCourse.create(:student_id => User.current.id, :course_id => params[:object_id])
+            @state = 0
+          else
+            @state = 1
+          end
         else
-          @state = 1
+          @state = 3
         end
-      else
-        @state = 3
       end
     else
-      @state = 4
+      @state = 5
     end
     respond_to do |format|
-      # format.html { redirect_to_referer_or {render :text => (watching ? 'Watcher added.' : 'Watcher removed.'), :layout => true}}
       format.js { render :partial => 'set_join', :locals => {:user => User.current, :course => Course.find(params[:object_id]), :object_id => params[:object_id]} }
     end
   rescue Exception => e
diff --git a/app/views/courses/_set_join.js.erb b/app/views/courses/_set_join.js.erb
index fb9b9924e..41ca263ce 100644
--- a/app/views/courses/_set_join.js.erb
+++ b/app/views/courses/_set_join.js.erb
@@ -12,7 +12,7 @@
         alert("您已经加入了课程");
     <% elsif @state == 4 %>
         alert("您已经的课程不存在");
-    <% elsif @state == 4 %>
+    <% elsif @state == 5 %>
         alert("您还未登录");
     <% else %>
 		alert("未知错误，请稍后再试");