[RESOLVED] Checkbox not work properly when clicked on quickly multiple times

[NGC4889]

I have done some code for checking treeview node

     Private Sub TreeView1_AfterCheck(sender As Object, e As TreeViewEventArgs) Handles TreeView1.AfterCheck
        If updatingTreeView Then Return
        updatingTreeView = True
        CheckNode(e.Node, e.Node.Checked)
        HasCheckedChildNode = 0
        updatingTreeView = False
    End Sub

    Private Sub CheckNode(node As TreeNode, isChecked As Boolean)
        If node.Parent IsNot Nothing Then
            HasCheckedNode(node.Parent)
            If Not isChecked And HasCheckedChildNode > 0 Then Return
            node.Parent.Checked = isChecked
        ElseIf node.Parent Is Nothing Then
            For Each cn As TreeNode In node.Nodes
                cn.Checked = isChecked
            Next
        End If
    End Sub

    Private Sub HasCheckedNode(node As TreeNode)
        For Each cn As TreeNode In node.Nodes
            If cn.Checked = True Then
                HasCheckedChildNode += 1
            ElseIf cn.Checked = False Then
                HasCheckedChildNode -= 0
            End If
        Next
    End Sub

what this code do:
1. If parent node is checked/unchecked, also check/uncheck all child nodes
2. If just one child node is checked, also check parent node
3. If the last child node is unchecked, also uncheck parent node

this code works fine.

Problem:
When I clicks quickly some of the checkboxes are checked and some no
E.g. sometimes I checked the parent node but all child nodes still remain uncheck


Is there a reason for this?
Please let me know if I missed anything.