I can not view my wireless network on my laptop even though I can find both my neighbors.?

I just moved in with my girlfriend and am trying to connect to her wireless network. I can pick up her neighbors but not hers. It is unsecured so no key is needed. I tried to do it manually but it still wont connect. I have a Linksys wireless g 2.4 card and her router is a zyxel Zyair. Any suggestions would be great. Maybe I am doing somthing wrong when i do it manually?