diff --git a/Tiobon.Core.Services/Ghre/Ghre_StudyRecordServices.cs b/Tiobon.Core.Services/Ghre/Ghre_StudyRecordServices.cs
index d44e01ab..f67db80d 100644
--- a/Tiobon.Core.Services/Ghre/Ghre_StudyRecordServices.cs
+++ b/Tiobon.Core.Services/Ghre/Ghre_StudyRecordServices.cs
@@ -646,11 +646,11 @@ public class Ghre_StudyRecordServices : BaseServices<Ghre_StudyRecord, Ghre_Stud
             }
 
             DateTime? dtCourseBeginTime = null;
-            if (dtCourseBeginTime.IsNotEmptyOrNull())
+            if (courseBeginTime.IsNotEmptyOrNull())
             {
                 try
                 {
-                    dtCourseBeginTime = Convert.ToDateTime(dtCourseBeginTime);
+                    dtCourseBeginTime = Convert.ToDateTime(courseBeginTime);
                 }
                 catch (Exception)
                 {
@@ -662,11 +662,11 @@ public class Ghre_StudyRecordServices : BaseServices<Ghre_StudyRecord, Ghre_Stud
             }
 
             DateTime? dtCourseEndTime = null;
-            if (dtCourseEndTime.IsNotEmptyOrNull())
+            if (courseEndTime.IsNotEmptyOrNull())
             {
                 try
                 {
-                    dtCourseEndTime = Convert.ToDateTime(dtCourseEndTime);
+                    dtCourseEndTime = Convert.ToDateTime(courseEndTime);
                 }
                 catch (Exception)
                 {