Hi Fernando,
Are you sure you are assigning a static IP address to the board that is in the same network where it is connected?
You can set the IP in the file Security.h. Look for the ENET_IPADDR define:
#define ENET_IPADDR IPADDR(169,254,3,3)
If you are using the IP 192.168.1.5, for instance then you have to change to:
#define ENET_IPADDR IPADDR(192,168,1,5)
Hope this helps,
Regards,
-Garabo