I don't know the kit in question, but i've seen it before - WEP and WPA may be 'standards' but i've come across too much wireless kit that will just not talk the same 'standard' as anything else.
Cheap unbranded OEM hardware is usually the worst offender, but the name brands seem to get things twisted occasionally. At least the brands generally update drivers, so the best bet is to just keep updating, most of the time it'll spring to life one day. They usually manage to get at least one flavour right too, so it's worth trying to see if it works with WEP rather than WPA, or vice versa. If they all fail then maybe it's something else going wrong.
WPA is the better protocol, but even the supposedly insecure WEP-64 is fine for home use IMHO - you're just trying to stop people casually logging on, rather than providing bomb proof security, so it's worth trying them all. If everything else fails then just disabling SSID broadcast plus a MAC address ACL is reasonable, that'll put it out of reach of any neighbour you're likely to have.