Think I've found an "undocumented feature" in the software. When I try to edit the log (affiliate tracking screen) it prompts me to put in a properly formatted date. Apparently, when you updated the order numbers with the date, you must have extended the year to 4 characters. Ushop doiesn't like that. You must edit it from "2001" to "01" and then it accepts the order change. Minor bug, FYI next update.
That actually sounds kind of familiar. Are you using version 3.4? Let me look and see if we released a fix for that... And if not, we'll try to make one available ASAP.