Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim item As DataGridItem
For Each item In DataGrid1.Controls(0).Controls
If item.ItemType = ListItemType.Footer Then
Dim txt As TextBox = item.FindControl("textbox1")
Response.Write(txt.Text)
End If
Next
End Sub