Can't use unique local address as default IPv6 gateway - why not?

Hi,

I changed my IP, and tried to move over my ipv6 address allocation to
it on the BTExact IPv6 tunnel website... and it didn't work. Creating
a new tunnel, however, worked fine. It's broken.

Anyhoo...

I don't want to go through the pain of changing ipv6 addresses in all
my configs, so I'm trying to remove a dependancy on btexact's
allocated address range, and am trying out unique local addresses.

I've hit a snag however. It (the kernel, /sbin/ip or whatever) won't
let me use a unique local address as the default IPv6 gateway. It's
strange that I can use the link-local one just fine (as well as
obviously the one from global btexact's allocated subnet).

Anyone know why?

Thanks

--
To reply, take of all ZIGs !!

Alternative email address: (E-Mail Removed)IG