There could be a few things going on. It's important that you remove (delete) all previous drivers, if you had any prior to installing the new driver. Be sure to do a search in your system for "W4S" and delete anything that comes up. Also try specifically looking in your Extensions folders and delete anything with W4S in its name.
After doing so, restart your computer and install the new driver. If things still aren't working, try going into your Extensions via System Preferences ( > System Preferences > Extensions) and making sure iTunes is checked.