vb.net write data to xml file

I am trying to write a vb.net program for a smart device, that writes the input from txt/combo boxes to an xml file. This file will be stored in the '/my documents/ data.txt' dir.  I plan to use active sync to push the data to the pc.  Here is what I have piced together so far,  the program creates the file, however does not populate with data.  I need to know what I should do next.

Dim t As New System.Data.DataTable
        With t.Columns
            .Add("eqnumber")
            .Add("OpStatus")
            .Add("keys")
            .Add("lights")
            .Add("glass")
        End With
        Dim r As System.Data.DataRow = t.NewRow
        r.Item("eqnumber") = Eq_Num.Text
        r.Item("opstatus") = ComboBox1.Text
        r.Item("keys") = ComboBox2.Text
        r.Item("lights") = ComboBox3.Text
        r.Item("glass") = ComboBox4.Text

        Dim ds As New System.Data.DataSet
        ds.tables.add(t)
        ds.writexml("\my documents\data.xml")