Ok, so now that the configuration is right, I have the problem that I don't see any nodes when I scan the network. The nodes are loaded with the code from your OTA example alter for 868MHz (see below).
#define auth_key "Libelium"
#define id_mote "Sensor_1"
// Powers XBee
I can also see that something is received and handled becasue a line including the Sensor name is printed to the Serial Monitor but it shows no nodes in the command line tool.
It works the same with a second sensors. Receives the signal but no node detected by the otap tool.
Notes: I use otap64 and I had to set the gateway to API mode 2 to receive anything.