I voided a check today, and then reversed the original invoice because it should not have been entered at all.  Now I have that invoice showing on the AP aging as a credit.  When I look at the GL accounts, they are correct after the reversed invoice.  How do I get this credit off of the aging?

Does the credit show up to be picked to pay in AP-F.

Sound like you have a discrepancy between the BKAPINVT & the BKAPCHKH files. In other words for some reason the payments and or credits don't match the invoices. Most likely the problem will be in the BKAPCHKH File. Use maintain database and look for those transactions involved.