Help. MAC Filtering Problem

So when I enable MAC Filtering on my modem settings, it will block my computer even if it is in the allowed devices list.

My modem is a 2Wire modem.
AT&T
Computer Using Wireless CISCO USB Adapter
While the other devices in the allowed section can connect but mine cannot.
Could it be because my computer is hiding my MAC Address?
I tried manually inputting it but no use it didn't work either.

Please help, thanks.