They confirmed that is was not the problem of the unit. They analyzed my five cars finding that are all made before 2006. They gave me two friendly prompt:
1 Before use V4.88 Digiprog III digiprog 3 (Digiprog3) Mileage Correction Tool, I should read carefully the manual in the CD and learn how to program mileage for my car. In this case, I have an idea what cable should I use.
2 If come across the error, first disconnect the unit and connect to my car again. The unit will guide me which cable should be used to carrying out mileage programming. When project mileage programming function, I’d better to disassemble dashboard and mileage chip.
I ordered a Digiprog III (Digiprog3) Odometer Correction Tool with the version V4.88 from a Chinese OBD2 vendor. When I programmed my VW Passat B5 2003 via OBD2 port, an error “No Connection” popped out in the screen of the unit. Then I tried it on BMW E36 1997, it failed either. Following I test more three cars VW Polo 2000, Peugeot 106 2001 and Nissan Micra 2003 C66, it still did not work. I wonder maybe I was knocked off by the dealer. I immediately connected the tech support from www.xcardiag.com/ by sending error pictures.