6to4 tunnel trouble

[Mike Crowe <mac@mcrowe.com>]

I'm using 6to4 with my static IPv4 address. Some sites
(e.g. ipv6.google.com, www.debian-administration.org,
ipv6.beijing2008.cn, other 6to4 hosts) seem to be working
fine. Unfortunately others don't seem to be working at all
(www.kame.net, ipv6.research.microsoft.com,
altavista.ipv6.digital.com.)

Is this likely to be due to some problem at my end or the 6to4 relay
I'm using? Here's a traceroute6:

traceroute to www.kame.net (2001:200:0:8002:203:47ff:fea5:3085) from 2002:xxxx:yyyy::1, 30 hops max, 16 byte packets
 1  2002:c058:6301:: (2002:c058:6301::)  105.361 ms  105.544 ms  104.932 ms
 2  stf.ge-1.3.0-33.core1.chi.bb6.your.org (2001:4978:1:410::ffff)  129.923 ms  130.377 ms  130.942 ms
 3  gige-g2-19.core1.chi1.he.net (2001:470:0:7f::1)  114.922 ms  112.454 ms  113.938 ms
 4  10gigabitethernet3-2.core1.sjc2.he.net (2001:470:0:3c::1)  170.925 ms  170.415 ms  182.92 ms
 5  10gigabitethernet3-2.core1.pao1.he.net (2001:470:0:32::2)  170.296 ms  170.033 ms  169.932 ms
 6  * * *
 7  * * *
 8  * * *
 9  * * *

Thanks.

Mike.