RadTreeView with recursive table

Private Function GetTreeData() As DataTable
        Dim dt As New DataTable()
        Dim dc As New DataColumn()

        dc.ColumnName = "_ID"
        dc.DataType = GetType(Integer)
        dt.Columns.Add(dc)

        Dim dc1 As New DataColumn()
        dc1.ColumnName = "_Name"
        dc1.DataType = GetType(String)
        dt.Columns.Add(dc1)

        Dim dc2 As New DataColumn()
        dc2.ColumnName = "_ParentID"
        dc2.DataType = GetType(Integer)
        dt.Columns.Add(dc2)

        Dim dr As DataRow

        Dim SqlClass As New SQLSERVER 'User defined Class to fetch data from DB
        Dim Reader = SqlClass.selectData("Select * from tbl_GroupCategory")
        If Reader IsNot Nothing Then
            With Reader
                If .HasRows Then
                    While .Read
                        dr = dt.NewRow()
                        dr(0) = .Item("_ID")
                        dr(1) = .Item("_Name").ToString
                        dr(2) = .Item("_ParentID")
                        dt.Rows.Add(dr)
                    End While
                End If
            End With
        End If
        Return dt
    End Function

Private Sub Load_Tree()
        With radTrvDetails
            .DisplayMember = "_Name" 
            .ParentMember = "_ParentID"
            .ValueMember = "_ID"
            .ChildMember = "_ID"
            .DataSource = Me.GetTreeData()
        End With
    End Sub