POP - cant cancel processing

After selecting post invoice there is no option to quit this selection. The only option is to save. If amistake is made by the user (eg wrong date entered when the date field canrsquo;t be overwritten) thenthe invoice has to be posted. It canrsquo;t be cancelled.If an error is made and post invoice is selected then the purchase order is finalised and then canrsquo;t beused again.