This is due to your laptop is detecting all possible wi-fi signals coming within it's range but not getting an IP address by which your laptop can connect to internet. In case of wireless networks, an IP address is routed to laptop or pc through a wireless router for connecting it to internet service provider. Besides, your laptop'll need a network key that should be matched with the same key configured by a particular wi-fi network that is being detected by your laptop.
In case, if you are entering the right network key and same problem occurs then better check network configurations and WEP settings of your laptop.
Hope this answer could be helpful for you. Thank you!