Allied Telesis AT-WA7400/EU - Manual (Page 220)

Appendix B: Configuring Security on Wireless Clients
220
Make Sure the Wireless Client Software is Up to Date
Before starting out, please keep in mind that service packs, patches, and
new releases of drivers and other supporting technologies for wireless
clients are being generated at a fast pace. A common problem
encountered in client security setup is not having the right driver or
updates to it on the client. For example, if you are setting up WPA on the
client, make sure you have a driver installed that supports WPA, which is a
relatively new technology. Even many client cards currently available do
not ship from the factory with the latest drivers.