I am trying to update an Access table using OLEDB in VB.Net 2005. I can add rows but I cannot update them.

Code to instantiate the Access database and table...
Code:
        Dim conn As New OleDb.OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" & db.Name)
conn.Open()
Dim oda As New OleDb.OleDbDataAdapter("select " & sqlCols & " from [" & txtOutputTable.Text.Trim
...