I always print my wrappers with the conformation and then take the book to suppermarket postal outlet to mail.  Up until yesterday they didn't
 scan the bar code, just dropped it into the box with correct postage added.  

I talked them into scanning it and, it won't scan, nothing comes up.  In the past all books sent out without being scanned always show up scanned eventually, and always show when they were delivered.  While I like having the delivery conformation, its kind of odd to me that they can't scan it but obviously some one does scan it.  It's much easier to take it to the outlet I use instead of waiting for the post office trip should I be concerned?  I'm only paying the what pbbs charges me.

I'm only paying the what pbbs charges me.

You mean you're not paying the extra 19 cents for DC?  Then you've been shorting the P.O. and are risking the people receiving your books getting a postage due notice.

It could be that the initial scan isn't working because it's not a real post office (I really have no idea) and I wouldn't be concerned about that (it's delivery confirmation, not a tracking number).  You should be paying the additional 19 cents for DC, though.  The fee you're paying to PBS isn't covering the whole cost of the delivery confirmation.

You are buying your postage there when you take it to them? If so and they have not been scanning it, then they probably have not been charging you. That is the only way I know of that they can get the 0.19 charge into their system. They (USPS) enter that they are selling a DC, then they scan it and their system sees the numbers are eDC an adjusts the price to the 0.19.

I have never attempted to mail my books from a supermarket postal counter so I can't say what their scanning process is. My clerks said that I shouldn't because they did not qualify as a USPS retail counter for the purposes of the 13oz rule and they lose too many packages.

Were they actually using a postal scanner or trying to run it across their own scanners or something? Their scanners might be programmed to scan the retail DC, but not have eDC entered into their database since I think that is the supermarkets database, not the USPS's.

I have them check to see if media mail or 1st class is cheaper then I add the postage and send it on its way.  When they scanned it to charge me nothing came up on the screen and they said the number was to long??

No one receiving the books has mentioned that they owed postage, and the first scan is usually long before it gets delivered.  So I'm stumped as to why it's unscanable.  The outlet in the grocery store uses the same thing the post office uses.