Jose,
Ok, depending on the version of Windows you have, the IPv6 ping command will fail without the scope ID appended to the end.
I am suspecting that these ICMPv6 packets may be getting dropped at the driver level, since you don't see the packets reaching the break point you set on the 6678. I am going to ask the 6678 driver team to help with this.
But first, can I get you to provide a little more info on your set up? Can you please describe your network topology? For example, how is your PC connected to the 6678? Is it directly connected via a crossover cable? Or do you have a router or switch in between? Or maybe you are using your corporate network?
Also, are you able to IPv6 ping from your Windows PC to another IPv6 Windows PC? For example, if your current Windows PC is connected to a router, and the 6678 is also connected to the same router, can you try connecting another Windows machine (or Linux, Mac, any standard PC running IPv6) to the same router and try to IPv6 ping between the PCs?
Actually, knowing if you are able to do this or not will be a very helpful data point.
Steve