Unsecured wifi network asking for router PIN no.

HI guys, there is a problem in my wifi network. It's unsecured as my flatmates use it. We stay in a hostel. So no password has been set for that. But whenever I try to connect to that network, it asks for a PIN no. We use a Linksys router. The error is like"YOU CAN FIND THE PIN IN THE INFORMATION THAT CAME WITH THE LINKSYS CORPORATION WRT120N OR ON A LABEL ATTACHED TO THE DEVICE".

WHAT COULD BE THE PROBLEM.....How can I resolve it?