Why don't my params populate ?

Trying to get an update with param to work, trying to populate a field with a string of text about 1k.  I don't get an error,  fields just don't populate.

            Dim cmd As New OleDb.OleDbCommand

            'VarChar DECLARE @msg VarChar 
            'cmd.Parameters.AddWithValue("@msg", Msg)

            '**** This works, but I don't want to worrry about ' and "
            'cmd.CommandText = _
            '    "DECLARE @msg VarChar " & _
            '    "UPDATE tblMsgs01 " & _
            '    "SET msg = '" & Msg & "' " & _
            '    "WHERE id = '" & sID & "'"

            '**** this does not work and I have to 'DECLARE @msg ...' or the SQL conn complains, ("You must declare scaler variable ...")
            cmd.CommandText = _
                 "DECLARE @msg VarChar " & _
                 "UPDATE tblMsgs01 " & _
                 "SET msg = @msg " & _
                 "WHERE id = '" & sID & "'"

            '*** Try 1, failed
            cmd.Parameters.Add("@msg", OleDb.OleDbType.VarChar)
            cmd.Parameters("@msg").Value = "test"

            '*** Try 2, failed
            'Dim param As New OleDb.OleDbParameter
            'param.Value = Msg
            'cmd.Parameters.AddWithValue("@msg", param)

            '*** Try 3, failed
            'cmd.Parameters.Add("@Msg", OleDb.OleDbType.VarChar)
            'cmd.Parameters("@Msg", msg)

            '*** Try 4, failed
            'cmd.Parameters.AddWithValue("@msg", msg)

            cmd.ExecuteNonQuery()

Select allOpen in new window