DataAdapter and using .Update to save dataset

[Wokawidget]

Public Sub Update(ByVal CommandText As String, ByRef MyData As DataSet)
        Dim Comm As SqlCommand
        If _Transaction Is Nothing Then
            Comm = New SqlCommand(CommandText, Connection)
        Else
            Comm = New SqlCommand(CommandText, Connection, _Transaction)
        End If
        Dim da As New SqlDataAdapter(Comm)
        da.UpdateCommand = Comm
        da.Update(MyData)
    End Sub

That's what I have.
It doesn't error, but it also doesn't update my DB.
I use (and I know * is bad, but it's testing) the following as the CommandText:

SELECT * FROM Customers

So I fetch a dataset using the above sql, and then I use the above update statement to save it. I know I am doing something REALLY daft.

Woka