function rollback($conv_type, $role_back_date, $rollback_file, $rollback_voucher, $voucher_id_intern)
 {
     include PHPGW_SERVER_ROOT . "/property/inc/export/{$GLOBALS['phpgw_info']['user']['domain']}/{$conv_type}";
     $invoice = new export_conv();
     $buffer = $invoice->RullTilbake($role_back_date, $rollback_file, $rollback_voucher, $voucher_id_intern);
     return $buffer;
 }