Networking on the DK-S7G2

I'm trying to get networking working on a project based on the Blinky ThreadX example. Using the NETX_DUO_Webserver as a reference, I added nxd and sf_el_nx to my project configuration. I've added a tx_application_define_user function which roughly mirrors that in the web server demo, but though I'm able to ping the host board when running the web server, I can't when I'm running my new project. I also try pinging out from the board, but never see any outgoing traffic on the network (no ARP requests or anything). Any thoughts on what I might be missing? My development machine and the demo board are on the same subnet (and same switch). I've actually plugged them directly together with a cross-over cable to make sure the switch wasn't doing something with the packets, and I'm still not seeing any outgoing traffic. 

void tx_application_define_user(void *first_unused_memory)
{
    UINT status;
    NX_PACKET * resp;
    /* Initialize the NetX system.  */
    nx_system_initialize ();

    /* Create a packet pool.  */
    status = nx_packet_pool_create(&pool_0, (CHAR* )"NetX Main Packet Pool", (1536 + 32), packet_pool_area,
                                   sizeof(packet_pool_area));

    status = nx_ip_create(&ip_0, (CHAR* )"NetX IP Instance 0", SERVER_IP_ADDRESS, 0xFFFFFF00UL, &pool_0,
                          nx_ether_driver_eth1, &NETX_TP, 2048, 1);
    status = nx_ip_fragment_enable (&ip_0);
    status = nx_arp_enable (&ip_0, (void *) &NETX_ARP, 1024);
    status = nxd_icmp_enable (&ip_0);
    status = nx_tcp_enable (&ip_0);


    nx_icmp_ping(&ip_0,IP_ADDRESS(192,168,2,15),"TEST",4,&resp,NX_WAIT_FOREVER);
}

Thanks much,

-Chris