When i drag and drop the tree view control to the page,
on the control a message is displaying like: Error parsing control:Object referance not set to an instance of an object
 

And then what value i can pass to the -populatetree- recursive  function

Can U please cut and paste the code
  


i called bellow function using        
                    Dim oTreeNode As New TreeNode
                    TreeView1.Nodes.Add(oTreeNode)
                    PopulateTree(0, TreeView1.Nodes(0))

but tree not displayed..........



Public Sub PopulateTree(ByVal ParentId As String, ByVal TVNode As TreeNode)
        Dim oDataView As New DataView(odataset.Tables(0), "CATEGORYPARENT='" & ParentId & "'", "CATEGORYNAME", DataViewRowState.OriginalRows)
        Dim oDataRow As DataRowView
        For Each oDataRow In oDataView
            Dim oTreeNode As New TreeNode(oDataRow("CATEGORYNAME"))
            'Dim oComboBox As New ComboBox
            If TVNode Is Nothing Then
            Else
             TreeView1.ChildNodes.Add(oTreeNode) 
               ' For Winform TreeView1.Nodes.Add(oTreeNode)
                PopulateTree(oDataRow("CATEGORYCODE"), oTreeNode)
            End If
        Next
    End Sub

Try Changing Line TreeView1.Nodes.Add(oTreeNode) in PopulateTree to 
TVNode.Nodes.Add(oTreeNode)
' For ASP .NET Use TVNode.Nodes.ChildNodes.Add(oTreeNode)
I guess thats the problem. 

Any Way here's the correct working code for asp.net

   Public Sub PopulateTree(ByVal ParentId As String, ByVal TVNode As TreeNode, ByVal odataset As DataSet)
        Dim oDataView As New DataView(odataset.Tables(0), "CATEGORYPARENT='" & ParentId & "'", "CATEGORYNAME", DataViewRowState.OriginalRows)
        Dim oDataRow As DataRowView
        For Each oDataRow In oDataView
            Dim oTreeNode As New TreeNode(oDataRow("CATEGORYNAME"))
            'Dim oComboBox As New ComboBox
            If TVNode Is Nothing Then
            Else
                TVNode.ChildNodes.Add(oTreeNode)
                PopulateTree(oDataRow("CATEGORYCODE"), oTreeNode, odataset)
            End If
        Next
    End Sub