diff --git a/DOAN.Service/MES/quality/QcDefectCollectionService.cs b/DOAN.Service/MES/quality/QcDefectCollectionService.cs
index b81004a..10d8fee 100644
--- a/DOAN.Service/MES/quality/QcDefectCollectionService.cs
+++ b/DOAN.Service/MES/quality/QcDefectCollectionService.cs
@@ -27,7 +27,7 @@ namespace DOAN.Service.MES.quality
         /// <returns></returns>
         public PagedInfo<QcDefectCollectionDto> GetList(QcDefectCollectionQueryDto parm)
         {
-            parm.DateTime = ConvertDateTime.ConvertLocalDate(parm.DateTime.Value);
+            parm.DateTime = ConvertDateTime.ConvertLocalDate(parm.DateTime ?? DateTime.MinValue);
             var predicate = Expressionable.Create<QcDefectCollection>()
                 .AndIF(!string.IsNullOrEmpty(parm.MaterialCode), it => it.MaterialCode.Contains(parm.MaterialCode))
                 .AndIF(!string.IsNullOrEmpty(parm.MaterialName), it => it.MaterialName.Contains(parm.MaterialName))