Why ppl still insist on using MAC filtering escapes me. Once you have a secured wireless connection, MAC filtering is pointless. It certainly doesn't add to your security, only more hassle.
Perhaps you made a typo? Try turning MAC filtering off for a moment (or off completely, permanently would be even better
). If that doesn’t help, perhaps there’s an incompatibility w/ your wireless security settings. Try disabling wireless security for a moment and try again.