Question : i have a VBA code work with windows XP but not with Vista?

Hi:
1 ' I have this code
2 Private Sub btnSave_Click()
3 MsgBox "1"
4 On Error GoTo Err_btnSave_Click
5 MsgBox "2"
6 If ControlesValidation = False Then
7 MsgBox "3"
8    Exit Sub
9 End If
10 MsgBox "4"
11 MsgBox strFunc
12 If Trim(strFunc) = "add" Then
 13   Me.AddUser = strUserName
 14   Me.UserDepartment = strDepartment
   
 15 Me.SerNo = DMax("[SerNo]", "tblEmployee") + 1
 16  MsgBox Me.SerNo & " =SerNo"
 17   If IsNull(Me.SerNo) Or Me.SerNo = 0 Then
 18      Me.SerNo = 1
 19   End If
20  End If
I do run my program at windows XP several PC's, it work good.
But if I run it on a PC have Vista operating system
It work up to line no 11, and display "add" , but it dose not enter the if statement after it.
I do use it with trim and without trim(mean line no 12), but nothing happen.
Please help.  

Answer : i have a VBA code work with windows XP but not with Vista?

it was becouse of the security of the vista