Are you sure you're using the right wireless password? Are you sure you're finding the proper wireless network? If I do a scan on my laptop, I get 3 other wireless networks belonging to neighbors, etc.
If you're not sure, reset your wireless password to make sure its what you think it is and try again. Just remember if you change it, any other wireless clients will have to be updated with the new password or they will lose access to the wireless router.
If you need more help, you'll have to explain your network setup in specific detail, like router, wireless config, other wireless clients in use, etc.