Contact the seller and manufacturer and ask for a replacement or a partial refund. Be nice - but send that picture. You may want to give them measurements for both so they know which is wrong - or maybe they should send you a whole unit they know they built right... I'm betting either the mount or the plate got mixed up from another model...
You do have it with the solid bar of the mount up right?
I installed per directions.... It sits on 2 large washers(about 2 inches long) that screw onto the through bolts from my panniers...The front holes fit perfect....it says 2017 AT on the package...I sent them something wednesday night...facebooked them... and called them and left voicemail...havent heard a thing yet...I was nice
Kurt and Martha (BDCW) are in the process of transitioning to living full time on the go, they've been working from Alaska this summer so far and I think are still working out the kinks. They also spend a ton of time out riding, testing out their products. They are great to work with, and once they get your messages I'm sure they will sort everything out for you!
Totally agree with Motowerx. Black Dog Cycle Works are the best at making great products and then standing behind them 100%. It does sometimes take a little time to get to them - especially right now as they are in Alaska, but I guarantee you once they get in contact with you they will stand behind their product. From your photo it looks like there might be a problem with your individual plate - I have once and it fits fine, so likely it is a one off error. I am sure BDCW will get you fixed right up as soon as they hear of your issue.
Happens even with SW-Motech...I'm about to have my right side carrier cut, stretched and rewelded for it to fit....smaller companies usually handle these issues well. In my case Fortnine credited me 100$ on the rack, but SW-Motech still claimed it was compatible with the 2019.