Don't get all columns with DataGridCommandEventArgs

Hello,
I have generatet a Web-Datagrid by using a SqlDataadapter and a dataset. I generate the dataadapter and dataset dynamically and read with a sql data from 2 tables. I also added 2 columns with the property generator in the datagrid for deleting and updating data.

When I want to update a row with following sub

Private Sub DtaGrid_UpdateCommand(ByVal source As Object, ByVal e As System.Web.UI.WebControls.DataGridCommandEventArgs ) Handles DtaGrid.UpdateCommand
' get line which was changed by using index for data key list value
Dim sKey As String = DtaGrid.DataKeys(e.Item.ItemIndex).ToString()

' get fields for changed line, start with cell 2
Dim sZelle() As String
Dim i As Integer
Dim j As Integer
Dim tb As TextBox ' fields are shown as text box in data grid
ReDim sZelle(oTabelle.AnzFelder - 1)
'Dim r As
Dim index As Integer
index = e.Item.ItemIndex


For i = 0 To (oTabelle.AnzFelder - 1)
j = i + 2 'starts with cell 2
tb = CType(e.Item.Cells(j).Controls(0), TextBox)
sZelle(i) = tb.Text
Next
ds.Tables(0).Rows(index).ItemArray = sZelle

index = e.Item.ItemIndex
' delete data from data source
oHlpSql.UpdData(da, ds, oTabelle.auswuser, index) 'does the update in ds and da
ConDtaGrid() ' bind datagrid
End Sub


My problem is now that,
e.Item.Cells(j).Controls(0) 'with j = 2
has only 2 cells (delete and update, which I generated in the grid. All the columns, which come dynamically from the dataset are not recognised.

Does somebody knows this problem?

Greetings,
Brigitte