I just mailed out a book where I paid .23 (taken out of my PBS account) for PBS DC, but did not purchase PBS postage.  I took it to the post office to purchase postage, and they said I would have to pay ANOTHER $1.05 to actually have the DC activated.  The post office worker did scan my PBS DC bar code, but then he stuck the new post office sticker (WITHOUT DC, since I wouldn't pay another $1.05) right on top of the PBS bar code.  

Two questions:  (1)  How will this turn out?  Since the original PBS bar code is now covered up, I won't get the quick credit I paid for, right?  And my assurance of getting my credit, even if receiver neglects to mark received, is no longer going to work.  (2)  What should I do the next time?  I think I must have to pay for both the PBS postage AND the DC, in order to get quick credit.  Right?  And...it was the same price to purchase postage at the P.O., so I didn't actually save money, which I thought I was going to do.

Your post office made a mistake.  Report them.  They were not trained correctly.  Please print out the directions that PBS has under "What's New" and take it with you.  (Over a year ago the procedures were changed.  The counter staff should know how to do this by now.)

It sounds like they may have scanned the bar code at the wrong point.  If they scanned it correctly, it should show up on the Details of the book order.  If they scanned at the wrong point, then it will not appear. 

Yes, your post office is wrong.

If you continue to have problems with them, have them put the postage only on the book, and then ask them to sell you a 23 cent stamp and put it on the book yourself.

That is 100% within the Post Office rules, although the clerks may give you a hard time about that too. Some clerks seem to believe that electronic Tracking is only OK if the postage is pre-paid, which is wrong. You can print out the rules right from the DMM (Domestic Mail Manual), which governs the rules for mailing, and show them to the clerk(s) who are giving you a problem. Local post offices cannot make rules that contradict the DMM.

The printable instructions Emily mentioned have proved helpful in the past.   The "What's New" link is near the Log Off link, in the top right corner of any page.  They should weigh the package, key in the zip code and then Stop.  Don't hit the "media mail" key.  Scan the bar code at this point, and their computer will give them the correct info.

What they said   Many postal employees were not properly trained after the USPS software update (was it Jan 2013?)

Your PBS Tracking works just fine.  The problem is they try to use the old method and push a bunch of buttons on their screen and get too far into the transaction before scanning the barcode.  The correct method (as listed on the PBS directions) is to weigh the package, key in the zip code, then I think there's just one or two screen buttons to push, then scan the barcode. 

They do NOT need to enter Media Mail, it comes up automatically now when the barcode is properly scanned.  If they are still pushing buttons at this point they have gone too far and the barcode is going to scan as invalid.

Thanks so much, everyone!  I found the document and printed it.  I will try this with the next shipment.

I've found that the cooperation of my postal office varies with who is working.  The person who was working that day was the same one who wanted to charge me $1.50 to hand-scan my prepaid package when I gave it to him.  He doesn't work the front very often, thank goodness.

ETA:  And, sure enough, my quick credit is still pending.

I carry the instructions to the USPO everytime they don't have this happen everyday , they told me I was the only one coming in with the scan already on Media mail since it may be a month between times they forget, I always have the how to with me.

I'm lucky... I use 2 POs locally and both of them are pretty much non-issues. I'd worry if I had to use a different PO, but 1 of the clerks from mine transferred to a station in the Southern part of the city so I could still luck out there ^.~ If I'm on the go for the day I still try to either start or wrap at one of the good ones since I don't trust the others and hear bad things about them.

I always use the pre paid postage. I don't have to go to the PO also. It might cost a bit more but not having to stand in line is worth it to me. My post office is pretty well trained...even if my favorite worker had to go retire!