You cannot set the OleDbCommand.Transaction property if it is already set to a specific value, and the command is in the process of executing. If you set the transaction property to an System.Data.OleDb.OleDbTransaction object that is not connected to the same System.Data.OleDb.OleDbConnection as the System.Data.OleDb.OleDbCommand object, an exception is thrown the next time that you try to execute a statement.