I have a problem about how to refresh the parent form treview data. In my program, When SQL table updated, In my Bo the ServerData changed Event received the notification. So I call  FrmMain.LoadMsg() to refresh the treeview data in Bo ServerDataChanged Event. I found the FrmMain.LoadMsg is running but the FrmMain's treeview not refresh. please told to me how to apply this function. (I using VB.net) , Thanks a lot.

    Private Sub SystemMsgBO_ServerDataChanged(ByVal e As System.Data.SqlClient.SqlNotificationEventArgs) Handles Me.ServerDataChanged

          MsgBox(e.Info.ToString() & ControlChars.CrLf & e.Source.ToString() & ControlChars.CrLf & e.Type.ToString())

           FrmMain.LoadMsg()

End Sub

      Thank you for you help! the code for  the LoadMsg and also the code for the BO event  as bellow. I think the main problem is how to refresh the parentform control through chilform. If the FrmMain Activated, I call the LoadMsg on the FrmMain treeview data refreshed.

    Public Sub SystemMsgBO_ServerDataChanged(ByVal e As System.Data.SqlClient.SqlNotificationEventArgs) Handles Me.ServerDataChanged

        '-- Show the query information to make sure it had been executed
        MsgBox(e.Info.ToString() & ControlChars.CrLf & e.Source.ToString() & ControlChars.CrLf & e.Type.ToString())
        FrmMain.LoadMsg()
    End Sub

'the following code in FrmMain
#Region "Load MessageTree"
    Private Sub LoadMsg()

        '-- Establish Locals
        Dim loMsgNode As TreeNode

        '-- Clear the tree
        CheckedTreeView2.Nodes.Clear()

        Dim MyMsgBo As New SystemMsgTitleBO
        Dim loParentID As String
        MyMsgBo.FillDataTable("select * from SystemMessageTitle" )

        '-- Cycle through all of the parent records
        If MyMsgBo.MoveFirst() Then
            Do
                '-- Create the new root node
                loMsgNode = New TreeNode(MyMsgBo.MsgCategory)
                loParentID = MyMsgBo.MsgCategory

                '-- Load any children nodes
                LoadMsgChildNodes(loParentID, loMsgNode)
                Me.CheckedTreeView2.Nodes.Add(loMsgNode)
            Loop While MyMsgBo.MoveNext()
        End If
        '-- Expand and show the last node
        Me.CheckedTreeView2.ExpandAll()
        Me.CheckedTreeView2.SelectedNode = CheckedTreeView2.Nodes(0)
    End Sub

    Private Sub LoadMsgChildNodes(ByVal ParentID As String, ByVal ParentNode As TreeNode)
        '-- Establish Locals
        Dim loMsgNode As TreeNode

        '-- Load the child records
        Dim loChildMsgBO As New SystemMsgBO
        loChildMsgBO.FillDataTable("select * from SystemMessage where MsgCategory='" & ParentID & "' and postto='All' or postto='" & SecurityBasics.CurrentUser.UserName & "'")

        '-- Cycle through the child nodes
        If loChildMsgBO.MoveFirst() Then
            Do
                '-- Create the node
                loMsgNode = New TreeNode(loChildMsgBO.MsgDetail)
                loMsgNode.Tag = loChildMsgBO.MsgCategory

                '-- Add to parent nodes
                ParentNode.Nodes.Add(loMsgNode)

            Loop While loChildMsgBO.MoveNext()
        End If
        '-- Clean Up
        loChildMsgBO.Dispose()
    End Sub
#End Region