I have an ex-SFO DONE5 I've been trying to get the online tool to let me pay for all week. Initially I was only getting 15012 errors. On Wednesday I called the AA ATW desk and the agent ran through my entire itinerary to check that there was actual D inventory. She suggested one changes and said that would make it though, except it didn't.

Since that time I not only continue to get 15012 errors, but also 9015 and 5685-2201 errors. At one point I was able to flip pretty reliably between 15012 and 9015 by changing my first segment from JL1 to AA5815 (AA codeshare number for same JL operated flight).

I've eliminated all codeshares since some comments upthread and elsewhere seem to correlate that with failures, and I've eliminated all LAN flights due to problems discussed earlier in the fall on the AA forum which I don't know are relevant since that discussion was about award booking.

The tool said the itinerary is validated and every segment has availability every time (including the segment that the AA ATW agent said did not have availability: LA601).