300C dropping DHCP relay packets

[graham_morrison]

Afternoon everyone.

As the title says i am having trouble getting dhcp relay packets through my 300C.  The setup i have is:

Client---L3 Switch with ip helper---Cisco ASA---wan---300c---lan

I can see through packet captures that the dhcp request is getting as far as the wan interface of the 300c.  The packet itself in Wireshark looks as it should with the correct Src and Dst etc.  That's the last i see of that packet.  I cannot see it being dropped in the logging but it never pops out the LAN interface.  The rule on the WAN interface is just and all----->Server Network---All so nothing should be dropping it from a rule point of view.  Just for my own sanity i created a new explicit rule just for the source and destination for all protocols and the hit count is 0 which shows its not even getting as far as the rule base.   I ran a capture on the LAN interface of the 300c and i never see any dhcp packers from the wan interface.  Is there some tick box for letting dhcp relay packets through?

The 300c is running 5.2.7, build718 and is in NAT mode.