Attaching a screenshot below. We have been using MyWell/Transnational since March of this year (we transitioned to it in anticipation of our migration to Rock in the fall) and in that time (prior to our instance of Rock being ready) migrated the vast majority of our monthly and one-time donors to the Transnational system. Everything there is working fine. Now that Rock is up and running any new giving that happens through our website is syncing correctly (payment is processed through Transnational, our bank account gets the funds, and we are able to report on the transactions from within Rock). 

However, we are having some trouble getting old transactions/donors to download and sync. For example, I have made a number of test donations on our website and those are showing up within Rock, but I am also a recurring monthly donor and those are not showing in Rock. I understand how to run the Download Payments function but am getting the message below. Any ideas what we are doing wrong that is keeping the downloaded transactions from syncing up with our database? My assumption is that we need to somehow match an ID # from Transnational with one in Rock...but how do we do that?

Any help would be greatly appreciated!