DHCP relay agent over QinQ on S5700 Switch

Recently I have configured a DHCP relay agent on a S5720 Switch, it works fine as manuals indicates with dhcp enable commands, dhcp relay select-server , dhcp  select relay on the interface vlanif , etc. 

I made same configuration over QinQ but clients dont receive Ip address, and dhcp messages are not being sended out the switch to reach DHCP servers.  We have communication between DHCP server an relay agent and other clients with static IP in the same vlan. So its not a problem of communication and cpu usage is fine. So I wonder if there is some kind of issue configuring Dhcp Relay Agent over QinQ (dot1q-tunnel ).I made captures in both interfaces and this messages (Bootp) are not sended out the dot1q-tunnel interface. 

Can you help me to clarify this?.