can't create a new voucher (sequence).

i cant create a new voucher, the error : "System does not support setup 'continuous' of number sequence %1."

my code :

ledgerJournalName = LedgerJournalName::find(ledgerJournalTableCopy.JournalName);

numberSeq = NumberSeq::newGetVoucherFromCode(ledgerJournalName.VoucherSeries);
voucher = numberSeq.voucher();

box::info(strfmt("New Voucher : %1", voucher ));

anybody can help me??