主题：动态加载时递归函数目录树不能生成

数据在动态加载时，递归函数生成的目录树不能生成，怎样才能在后台生成呢，

Dim tv As WinForm.TreeView = e.Form.Controls("TreeView1")
Dim nd As WinForm.TreeNode
Dim dt As DataTable = DataTables("分级码表")
tv.StopRedraw()
tv.Nodes.Clear
Dim lst As List(Of String) = dt.GetValues("物资编码")
For Each dr As DataRow In dt.Datarows
    If dr("上级编号") = Nothing Then    
        nd = tv.Nodes.Add(dr("物资编码"),dr("物资名称"))
        Functions.Execute("物资递归函数",nd,dt)
    End If
Next
tv.ResumeRedraw()