Devolo dLAN USB driver problem!

Im trying to connect my pc to my devolo dlan duo using usb instead of ethernet, however when i try and install the drivers (downloaded the usb drivers from their site), a box pops up telling me its removing old files and replacing them, and then it says the drivers were installed correctly. However windows still doesn't recognise the device. When i go into devices and printers it recognises it as a "USB powerline adaptor" but has a small exclamation mark and says it has no drivers installed. I've used windows to search for drivers but that hasn't worked. It keeps saying it doesn't find any. I've rebooted several times, unplugged it and plugged it back in, reinstalled the drivers but still nothing. Any ideas?
thankyou

BTW im running windows 7 professional 64-bit. I had xp 32-bit and had the same problem but after a lot of frustration it worked but i cannot remember how i did it :stupid:

Well I've found the driver CD that came with the device but still nothing. I've tried many times to manually install the drivers by using update driver and choosing the folder the drivers are in. I also chose the CD for windows to find the drivers in but it claims it doesn't find any. Any ideas why?
The files which I presume are the drivers are called usbeth.inf, usbeth.cat and usbeth.sys. However windows doesn't find them as drivers and therefore doesn't install them.