The issue with the router channels is a regional one. In the U.S. it tops out at channel 11. I believe that channels 12 and 13 are for Europe and possibly Asia. So, if you had a U.S. version computer and you traveled to Europe, you wouldn't be able to "see" a router that was using channels 12 or 13.
The various jurisdictions have some of the frequencies defined in the WiFi specs. already assigned for other purposes, so those channels must be blocked out on the adapter so as not to interfere with the equipment already assigned to those frequencies.
Perhaps this is your issue?