diff --git a/app/controllers/student_work_controller.rb b/app/controllers/student_work_controller.rb
index 0efa0aa66..b6f69a4da 100644
--- a/app/controllers/student_work_controller.rb
+++ b/app/controllers/student_work_controller.rb
@@ -190,8 +190,10 @@ class StudentWorkController < ApplicationController
             if @work.student_score.nil?
               @work.final_score = @work.teaching_asistant_score
             else
-              final_ta_score = BigDecimal.new("#{@work.teaching_asistant_score}") * BigDecimal.new("#{@homework.homework_detail_manual.ta_proportion}")
-              final_s_score = BigDecimal.new("#{@work.student_score}") * (BigDecimal.new('1.0')  - BigDecimal.new("#{@homework.homework_detail_manual.ta_proportion}"))
+              ta_proportion = @homework.homework_detail_manual.ta_proportion if @homework.homework_detail_manual
+              ta_proportion = @homework.homework_detail_programing.ta_proportion if @homework.homework_detail_programing
+              final_ta_score = BigDecimal.new("#{@work.teaching_asistant_score}") * BigDecimal.new("#{ta_proportion}")
+              final_s_score = BigDecimal.new("#{@work.student_score}") * (BigDecimal.new('1.0')  - BigDecimal.new("#{ta_proportion}"))
               final_score = final_ta_score + final_s_score
               @work.final_score = format("%.2f",final_score.to_f)
             end