Sending IPv6 over Ipv4 packet from Ostinato and not getting response.

Hi All,
I have connected two systems point to point. And try to send an IPv6 over4 packet from the Ostinato tool.
But not getting any response from the other side.
For ICMP packet I am getting no response error.
While for normal IPv4 and IPv6 it is working.

Please help me regarding settings for IPv6 over4.