Strictly speaking, they are not passwords but network or encryption keys.

 

There are two types of WEP keys - ASCII and Hexadecimal, but both are very specific in length and characters used.  From your description, sounds like your wireless adapter is expecting an ASCII WEP key: 5 characters for 64bit WEP encryption and 13 characters for 128bit, and for HEX keys, 10 characters for 64bit and 26 for 128bit.  Unfortunately, some brands only support one type and not the other.

 

What brand of router and wireless adapters are you using on the rest of the network?  If they are from the same brand or make and that you are using their wireless client software, it is possible that you have been using a Passphrase instead of a WEP key to connect to your network.  What a Passphrase does is like a key generator primer, and the wireless client software uses the same Passphrase to generate the actual network key used for encrypting the network.  The problem lies with Passphrase is that only certain brands support this alternative method, e.g., Linksys, so if you have a 3rd party wireless adapter that doesn't support it, you will need to find the actual WEP key in use on the router and enter on your client.  Here's an example of what a Passphrase and WEP keys setup look like on my Linksys WRT54G (the Passphrase is used to generate 4 WEP key, only one of which is in use):