::ffff:192.168.0.xx, destination unreachable

Hello,
on my shiny little box from inception hosting (the one with 64mb of ram, 1 private ipv4 natted and 5x ipv6) I want to telnet my lan ip (192.168.0.xx) with the ipv6 mapping.
If I do:

telnet ::ffff:192.168.0.xx PORT

it works, but if I specify an address:

telnet -b BOX-IPv6-Address ::ffff:192.168.0.xx PORT

I obtain "destination unreachable".

Someone can give me a clue?

Thanks