All I can write is the product is defective. Get a refund and try another one.
Remember I can only look into this with full details. Sometimes it's some no-name thing and we are at an impasse but here the details were missing from the onset. Try telling more.
I'm using Windows 10 on a laptop that's also connected to a drawing tablet via VGA that doubles as a secondary monitor. When I first bought the tablet, I had no issues with it, and could use it in extended mode with no problems. Now, however, all of a sudden, if I try to use it in extended mode, it starts acting up. For some reason, no matter what I do, it's interpreting the total space between the two monitors as one single space. So when I use the pen input on the exact center of the tablet, it interprets that as the very edge of the laptop screen. 75% of the way across the screen, it interprets that as the center of the laptop screen, etc. Does anybody know of an easy fix so I can use the extended display properly again? I've already tried reinstalling the tablet and display drivers to no avail.