Sub UpdateSave()
OrigFile = ThisWorkbook.Path & "\" & ThisWorkbook.Name
ThisWorkbook.SaveAs Left(ThisWorkbook.FullName,
Len(ThisWorkbook.FullName) - 4) & "_old_" & Format(Date, "mmddyyyy")
OldFileName = ThisWorkbook.Name
Workbooks.Open fileName:=MacroPath & MacroFileName, UpdateLinks:=False,
ReadOnly:=True
On Error Resume Next
Application.Run "'" & MacroFileName & "'" & "!ModUpdate.MacroUpDate",
MacroFileName, OldFileName
On Error GoTo 0
MsgBox ("Original file is saved as " & OldFileName & "." & Chr$(10))
ThisWorkbook.Save
Application.DisplayAlerts = False
Workbooks(MacroFileName).SaveAs fileName:=OrigFile
Application.DisplayAlerts = True
ThisWorkbook.Close
End Sub

The error msg is on this line of code
Application.Run "'" & MacroFileName & "'" & "!ModUpdate.MacroUpDate",
MacroFileName, OldFileName

Thanks in advance.