Apple 23 Cinema HD Display vertical position offset

[chanyikchung@gmail.com]

I have just purchased an USB 2.0 Display adaptor in order to extend the display on a 23" Apple Cinema Display HD (Aluminium version), from long time ago. However, after installing the latest driver for mac (V 2.0), the image of the extended display seems shifted upward.

I am currently using Macbook air 4.2 (2011 mid), running mountain lion 10.8.4 and a extended display (24 LED Cinema display via thunderbolt port)

I want to hook up one more display thru the USB port for more display area.

Please see the attached photo for the illustration. I am new to the forum and hope someone can share their thoughts if you also encountered the same problem.