Has anyone had issues adding an IPv6 route in Ubuntu 10.04?

Just curious as I've done:

#route --inet6 add 2002:20:20:20::/64 gw 2002:20:20:20::1 dev eth0

~and~
# ip -6 route add 2002:20:20:20::/64 via 2002:20:20:20::1

and neither worked. Using the route command returned "SIOCADDR: Invalid Argument" and the ip command returned "RTNETLINK: Invalid Argument".

I installed radvd and still have the same issues.

I googled the terms and found someone who believes it to be a bug. Is there a workaround or fix or am I just not doing something correctly?

Thanks!
(ps, those ipv6 addresses are not real)