A MAC address XX-XX-XX-XX-XX-XX has 48 bits, with each XX being the hexadecimal representation of 8 bits (an octet or byte). The first three octets XX-XX-XX represent a code assigned to the manufacturer (vendor) and according to this official list from the IEEE - http://standards.ieee.org/regauth/oui/oui.txt - one of Apple's vendor codes is D8-30-62. I assume this is what you have.
I'm totally lost as to why the MAC input form in the D-Link web interface would check for the first octet (byte) to be 0. That would be a very poor implementation. Maybe it's a bug and was fixed in more recent versions of the firmware. Are you running the latest firmware version for your model/revision?
Also. Are you sure you inputted the MAC correctly?