adding edit button to datagrid problem

[slinky]

I had a successfully deployed datagrid reading an XML file and
showing the data:

Private Function MakeDataView() as DataView
Dim myDataSet As New DataSet()
myDataSet.ReadX ml(Server.MapPa th("TimberSales .xml"))
Dim view As DataView = New DataView(myData Set.Tables(0))
view.AllowDelet e = False
view.AllowEdit = True
view.AllowNew = False
view.Sort = "Year ASC"
Return view
End Function


Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs)
Dim view as DataView = MakeDataView()
dgTimber.DataSo urce = view
dgTimber.AllowS orting = True
dgTimber.DataBi nd()
End Sub
_______________ _______________ _______________ _______________ __________

I wanted to add an "Edit" button as desribed at:

http://msdn.microsoft.com/en-us/library/aa984288(VS.71).aspx:

Private Sub dgTimber_EditCo mmand(ByVal source As Object, _
ByVal e As System.Web.UI.W ebControls.Data GridCommandEven tArgs) _
Handles dgTimber.EditCo mmand
dgTimber.EditIt emIndex = e.Item.ItemInde x
dgTimber.DataBi nd()
End Sub

Dim newData As String
Dim aTextBox As TextBox
aTextBox = CType(e.Item.Ce lls(1).Controls (0), TextBox)
**** says "aTextBox" is not declared, (?)
newData =
aTextBox.Text **** says
"newData" is not declared, (?)

Private Sub dgTimber_Update Command(ByVal source As Object, _
ByVal e As System.Web.UI.W ebControls.Data GridCommandEven tArgs) _
Handles dgTimber.Update Command
Dim quantityCell As TableCell = e.Item.Cells(6)
Dim quantityBox As TextBox = _
CType(quantityC ell.Controls(0) , TextBox)
Dim quantity As Integer = System.Int32.Pa rse(quantityBox .Text)
dgTimber.EditIt emIndex = -1
dgTimber.DataBi nd()
End Sub


When I hit the Edit Button I get this:

Invalid postback or callback argument. Event validation is enabled
using <pages enableEventVali dation="true"/>
in configuration or <%@ Page EnableEventVali dation="true" %in a
page. For security purposes, this feature ....etc.

Does anything obvious stabd out as the potential probelm? Thank You!