This.

Your new reservation middle name has to EXACTLY match how the middle name was entered on the original flight, but good luck on figuring that out. Full middle name, initial only or blank.

I book and change flight all the time for my employees that may have not been booked by me and it is almost a flat out scam by WN to deny people access to the flight credits. First, last, RR# and confirmation # should be all you need...but nope. I am a die hard WN fan but it is one of the few areas that I think WN is underhanded and slimy in their operations.