problem with retrieving the contents of a textbox in a loop

Hi,
 I have 10 textbox controls in a table in the web page.
 I want to iterate through the controls and if the control is a textbox, read its content and add it to the datarow in a datatable
 I have  the following code but for some reason, the table is empty after the run. I do not get any errors when i run it.
 

For Each ctr In Me.Controls

            If TypeOf ctr Is TextBox Then
 
                Dim abc As String = ctr.ToString
                Dim dt_row As DataRow
                dt_row = dt_userinfo.NewRow
              ...