AP-C is date sensitive.. if you say the invoice date is for the 28th then all items received after the 28th are not on the list to pick from, that might be your issue, just a guess.
 

There are two dates in PO Invoices, the invoice date and the post date.  The invoice date is the date on the invoice, the post date is the date that can not be before the receiver date.  MY AP person always makes the post date the date of the receiver or later.

The invoice date is the date on the invoice.  The post date should almost always be the date it is entered into DBA unless you are facing an end of the year situation.
 
DBA ages from the invoice date when determining when to pay the bill.

Quote from wildco   on 10/05/06 at 08:52:52:

Maybe I'm just picky, but I like to be able to create any report on any data for any date range and know that it will be accurate. The fact you acknlowledge that at the end of year they should agree indicates to me that the concept applies any time.
 
Is there some reason why it's bad in DBA to enter the post date in the past?

Actually, that is no longer true. The limits on dates allowed in AP-B & AP-C as well as payment dates in AP-H will keep the aging and GL in agreement.

Quote from wildco   on 10/06/06 at 09:48:16:

 
I was under the impression that the Invoice Date is the date DBA uses to age the bill in AP-Aging, and transaction date is the date DBA uses to post the invoice to the General Ledger in RP batch. If a prior period date is used for posting the invoice, that would change the prior period General Ledger balance for Accounts Payable - would it not?  

Certainly the transaction goes into DBA on the date the transaction is posted in GL-O.  But, I am 99% certain when it posts the amounts to the income statement/bal sheet, it uses the invoice date, and not the post date.  
 
Maybe Lynn can verify this, I dont want to give out incorrect info.
 
If you have reset your period close date at the end of a fiscal year, you will be unable to enter a transaction with a prior date, hence my statement about running into trouble at the end of the year.  Of course, you can roll the date back, enter the invoice, and reset the date, but at some point you need to close the books so you can pay taxes, etc.  At that point, I think you are better off putting in the transaction on the first date of the new year.
 
kevind:  DBA does make a transaction to RNI and inventory when something is received, and you now have to pay for the goods (the accrual system).  Then, when the invoice is posted, it removes it from RNI and puts it into AP.  I should have been more specific.
 
We have always done our receiving/POs this way and do not experience any problems.