[RESOLVED] Determine check only one node at parent

[nUflAvOrS]

Hi all,
I created a treeview that's only allowed user check on only one node at all parent. Below is my code.

Dim CheckOnlyOne As Node
'checked
k = 0
Set CheckOnlyOne = Node.FirstSibling
j = 0
If CheckOnlyOne.Checked = True Then
    Do Until CheckOnlyOne Is Nothing
        If CheckOnlyOne.Parent Is Nothing Then
            If CheckOnlyOne.Checked = True Then
                j = j + 1
            End If
        End If
        If j > 1 Then
            
            MsgBox "Can select one department only", vbCritical, "Error to select department"
            Node.Checked = False
            Exit Sub
        End If
        Set CheckOnlyOne = CheckOnlyOne.Next
    Loop
End If

The problem is when running debug with breakpoint the node is successfully to unchecked.However, when debugging end the node was checked back.

How to solve my problem ?

Thanks in Advance.