Not Receiving Raw Ethernet Packets

I am trying to communicate with an external board containing an FPGA and some other hardware using Ethernet. The firmware is designed to receive and send raw Ethernet packets. However, when I run the program I am able to send communications to the board, but I don't receive any reply.

I'm using Ubuntu 14.04 LTS on an HP laptop. I am using a root user account to send and receive the raw packets (and then set up a pipe if I need to send it to a non-root user). I am also using Wireshark to check the Ethernet traffic. I can see the Ethernet packets being sent out both in my pipe and on Wireshark and they look fine. I've also checked that my Ethernet interface is set to promiscuous mode to make sure I'm not missing anything (Wireshark is set to the same). Nonetheless I never see any packets returning from the board, only packets I've sent as well as some DHCP, ICMPv6 and MDNS packets.

I know that the board is working properly because I have the system set up on a different computer running Windows. I've checked the Ethernet packets being sent from the windows machine and they are identical to to those being sent by my hp laptop (except of course for the source MAC address), but on the windows machine this elicits a response from the board, where as I receive nothing with my laptop. I'm connecting to the same physical board so the same signals into the board should get the same responses.

I am new to this kind of stuff, but I have to assume that the board is indeed sending out Ethernet packets but I am for some reason unable to capture them. I have no idea how I might go about debugging this. Any help would be greatly appreciated.