Airport Extreme wireless password not working

I recently purchased an airport extreme and connected it to my cable modem and iMac G5. I proceeded through the Airport Utility, chose "Set up a wireless network" and entered a WPA/WPA2 password. After set-up the extreme's green light was on and I was surfing the web on my G5. I then checked for the wireless network on my MacBook. I located the network I had created and entered the password I had just set but got a "connection failed" message. Maybe I'm missing something obvious since I've never used airport utility before. Please let me know if anyone can help. Thanks.

Sorry not to have an answer but perhaps a related problem. An Airport Extreme that has been happily running with the same WAP password for a couple of years suddenly returns 'Incorrect Password' when I try to connect from one of my MacBook Pros. Rebooting everything seems to fix it temporarily, but it recurs after a while (perhaps after invoking Internet sharing for another laptop (trying to share a GPRS dongle). Any guidelines most welcome. Thx.