diff --git a/My Project/AssemblyInfo.vb b/My Project/AssemblyInfo.vb
index ff00a98..b35a75f 100644
--- a/My Project/AssemblyInfo.vb	
+++ b/My Project/AssemblyInfo.vb	
@@ -62,5 +62,5 @@ Imports System.Windows
 ' by using the '*' as shown below:
 ' <Assembly: AssemblyVersion("1.0.*")> 
 
-<Assembly: AssemblyVersion("2.3.10.4")>
-<Assembly: AssemblyFileVersion("2.3.10.4")>
+<Assembly: AssemblyVersion("2.3.11.4")>
+<Assembly: AssemblyFileVersion("2.3.11.4")>
diff --git a/NcComm/M_Num.vb b/NcComm/M_Num.vb
index 04717ad..48a0906 100644
--- a/NcComm/M_Num.vb
+++ b/NcComm/M_Num.vb
@@ -1580,7 +1580,11 @@ Namespace Num
       Public Overrides Sub DPlcVariables_WriteVariables(sz_var_names As String, sz_values As String)
          Dim value As Short = 0
          If Not Short.TryParse(sz_values, value) Then
-            EgtOutLog("Write variable: " & sz_var_names & ", value:" & sz_values & " failed!")
+            If Not IsNothing( sz_values) then
+               EgtOutLog("Write variable: " & sz_var_names & ", value:" & sz_values & " failed!")
+            Else
+               EgtOutLog("Write variable: " & sz_var_names & ", value:nothing failed!")
+            End If
             Return
          End If
          Dim _ret As Short = objDPlcVariables.WriteVariables(sz_var_names, value)