If an anticipated disbursement when billed hasn't been incurred by the BPO posting you can do one of two things:
Select General Postings.
Select AD and post a minus value on the matter within General Postings.
Click on SIB and bill the minus AD with the original disbursement that should of incurred the AD.
You can also do a reversal of the BPO by following the below steps:
Select General Postings and tick in the Reversal box.
Pick BPO transaction and reverse the original disbursement (if no monies allocated to the disbursement).
If monies are allocated just do a BPO minus without the Reversal box selected.
After the minus BPO post another positive BPO selecting the relevant Anticipated disbursement to incur.
Bill the minus and positive together via a SIB posting in General Postings.
If the balances can be incurred due to the AD having been paid but is not in the matter balance totals, please raise a new case online and reference the title of this article.