Criteria for picking up vouchers for budget check

Hi,

We are on PeopleSoft 9.2. There are few vouchers which didn't get picked up for budget check. Below is the result of the query.

SELECT A.VOUCHER_ID, A.BUDGET_HDR_STATUS, A.ENTRY_STATUS, A.APPR_STATUS

  FROM PS_VOUCHER A

  WHERE ( A.VOUCHER_ID IN ('XXXXXX))

Budget Status= N

Entry Status= P

Approval Status= P

Some of the vouchers are PO Vouchers while others are Non-PO. Is there any other criteria for budget check ?

Thanks,

Debolina