diff --git a/IRaCIS.Core.Application/Service/Reading/ReadingCalculateService.cs b/IRaCIS.Core.Application/Service/Reading/ReadingCalculateService.cs
index fc52cf7dd..35688865a 100644
--- a/IRaCIS.Core.Application/Service/Reading/ReadingCalculateService.cs
+++ b/IRaCIS.Core.Application/Service/Reading/ReadingCalculateService.cs
@@ -309,7 +309,7 @@ namespace IRaCIS.Core.Application.Service
 			{
 				SubjectId = visitTask.SubjectId,
 				VisitTaskId = visitTaskId,
-				SubjectVisitId = visitTask.SourceSubjectVisitId.Value,
+				SubjectVisitId = visitTask.SourceSubjectVisitId!.Value,
 				QuestionInfo = questionInfos,
 				CriterionId = criterionId,
 				TrialId = visitTask.TrialId,