|It could be the wireless encryption standard being used by his router that isn't compatible with your laptop's wireless adapter.|
Broadly speaking, the three main encryption standards are WEP, WPA, and WPA2, with WEP being the oldest encryption standard of those three.
Many older wireless laptops can only recognise WEP wireless keys.
Less older ones might recognise a WPA key but not a WPA2 key.
If that's the reason for the problem, the router may have to be reconfigured so that's it's using WEP wireless encryption. Be aware however that WEP encryption is the easiest standard to hack into.