Why can't I get online w/ Ubuntu and D-Link DIR-655 router?

My computer “sees” the network but I am not able to connect. I started with Ubuntu 64bit 10.04 LTS and upgraded yesterday to 10.10 thinking that might help. Nope. I’m now upgrading to 11.04 hoping it will work…I have a security key and password to input. I tried changing the settings to WPA Enterprise instead of Personal under “Configure VPN” and this gives a box for a key (not sure if it’s the key I have though) but it requires you to search for a file rather than input a string of text. I have a string of text. With WPA Personal, it only has a place to type a password, not the key. I’m stumped and already tried the Ubuntu forums. Any ideas? Thanks.