WiFi doesnt scan all networks

Hi,
I have recently purchased an old macbook. It has a broadcom wireless card in it. I have been advised of a kext to use to get it all working. Currently when I click on the airport icon on the taskbar it comes up with a list of networks but doesnt detect my network which other computers can use fine.
If I open the device in system profiler I can see my network in there, but obviously cannot connect to it this way.

I can connect to all other networks without an issue. Can anybody suggest what I can do. I have the broadcom kext to use but I dont know how to replace the current kext with the new one. Or is there just something small to change to get it working with my network.

Thanks
samp17