It may be your laptop (or whatever device you're trying to connect) that's not compatible with that length of password, or not compatible with the encryption type you've set in the router's wireless settings. Applies particularly to older laptops and other wireless-enabled devices.
Try setting a shorter wireless password in your router setup or change the encryption type.
If using WPA2 encryption, try a 12 character password (that's plenty strong enough to secure your network. All my Netgear routers in my various offices come with a preset 12 character passphrase and all my devices can connect fine. I never alter the preset passphrase, there's no need. Every Netgear router has it's own unique preset passphrase so that's good enough...