Did you use the latest software Rev 1.07 for the PCSU200 ?
It contains the driver install too.
Available here: https://www.velleman.eu/support/downloads/?code=pcsu200&type=
If still not working, you can download the Windows 7 driver here:
https://app.box.com/s/br3hkbsr13jgwbtx1nrrh5p09bucbjtn
In 64 bit version of Windows 7, you have to disable driver signature enforcement to install the driver:
Press F8 when Windows is booting up until you get the Advanced Boot Options menu, then select “Disable Driver Signature Enforcement”.