I know your frustration.  I am self taught on DBA.  Here is what I would do.  First I never change anything in the BKAPINVT or any other file itself.  I make all corrections either with vouchers or GL-B.  
 
Your TB is $0.00, did you make a GL entry for the amount that GL-A stated.  If so reverse it.  The GL-A does not give you the ending balance of A/P account only what has transpired during the month.  
 
Post to the GL.
 
Run GL-E.  Look at your ending balance (not the net transaction). That is the number you want to match your aging not GL-A.
 
If it does not match.  Time to audit one by one.  
 
1. Go thru your paper invoices that have been entered but not paid yet and compare to your aging.  
 
2. If everything is there then print the GL-E A/P account transaction for the current month (to start with) and compare to your paper invoices that were entered during the month.  My experience is that there is a credit and debit for the same amount canceling each other out in your A/P account.  If your TB was at $0.00 then it was more than one invoice so you might not match 1:1 on your debits and credits but to a lump sum in the debit side.
 
3. Next check the expense or asset account (GL-E) that that invoice should be debited too.  There is probably a debit and a credit for the same amount canceling each other out.  Again things may not match 1:1.
 
4. Make a GL entry for that amount debiting the expense or asset account and crediting your A/P account.
 
5. Post then run GL-E A/P account again.  It should match up to your A/P aging.  
 
Remeber GL-A only gives what has occured during the month not your TB total.
 
Hope that helps.