LoRaWan_AT_slave example does not change the keys with the AT+NWKSKEY command

[JTLGE]

this is what I see:

###### AppSKey:   2B:7E:15:16:28:AE:D2:A6:AB:F7:15:88:09:CF:4F:3C

###### NwkSKey:   2B:7E:15:16:28:AE:D2:A6:AB:F7:15:88:09:CF:4F:3C

AT+APPSKEY=?

2B:7E:15:16:28:AE:D2:A6:AB:F7:15:88:09:CF:4F:3C

AT+APPSKEY=2B:7E:15:16:28:AE:D2:A6:AB:F7:15:88:09:CF:4F:3C

AT_ERROR