arduino 2560 driver installation problem

Hello,

I've bought an Arduino méga 2560 compatible on banggood.com. I can't install the driver on windows 7. (I've also an Uno, a mega and a nano that I've installed whithout any problem) I've been on the device in the control panel and tried to install the driver by specify that's on my computer in the arduino/driver directory.

Does someone have an idee ? Thanks a lot for your help

ps. excuse my english....

Which one ? This one has a CH340G usb-serial chip: http://m.banggood.com/Mega2560-R3-ATMEGA2560-16AU-ATMEGA16U2-Board-With-USB-For-Arduino-p-940935.html

A driver for the CH340G can be found at www.wch-ic.com