You can't create and use /proc/net files in the same way as you did for the /var/dhcp.leases because anything in /proc/net is a virtural system file. More about /proc can be found here: http://linuxdevcenter.com/pub/a/linu...inuxAdmin.html
From the error, it looks like you're trying to load an IP6 address, as opposed to the standard IP4. I'd double check the dhcp.conf file to make sure you loading what you really want. If you do want an IP6 address, you probably need to double-check the documentation to see how IP6 should be implemented under the dhcp.conf file.