If you can connect to an open wifi but not to your wep encoded wifi then you need to check - and double check - your wep key. Does it have all the letters/digits - a 128 bit key has 26 letters/digits for example. Have you typed a letter O for a zero and things like that.

I had a client that swore blind his wep key was correct but he couldn't connect. I got him to retype the key and he used letter O in place of zero and there is no way that is ever going to connect. When he corrected that it worked and he had his connection.

Digits can be from 0 to 9 and letters A to F - anything else and you have no connection.