About LoRaWAN problem in Arduino

Hi Guys,

I have some problem about the LoRaWAN downlink problem. Although i can connect the device and uplink to device, the downlink have not operation. Have someone can help me? Please!!!

This is my Arduino code:

void do_send(osjob_t* j){
// Check if there is not a current TX/RX job running
if (LMIC.opmode & OP_TXRXPEND) {
Serial.println("OP_TXRXPEND, not sending");
software_Reset();
} else {
// Prepare upstream data transmission at the next possible time.
LMIC_setTxData2(1, mydata, sizeof(mydata)-1, 0);
Serial.println("Packet queued");
Serial.println(LMIC.freq);
Serial.print("LMIC.txrxFlags: ");
Serial.println(LMIC.txrxFlags, BIN);
Serial.print("LMIC.dataLen: ");
Serial.println(LMIC.dataLen, DEC);
Serial.print("LMIC.dataBeg: ");
Serial.println(LMIC.dataBeg, BIN);
}
// Next TX is scheduled after TX_COMPLETE event.
}

void onEvent (ev_t ev) {
Serial.print(os_getTime());
Serial.print(": ");
Serial.println(ev);
switch(ev) {
case EV_SCAN_TIMEOUT:
Serial.println("EV_SCAN_TIMEOUT");
break;
case EV_BEACON_FOUND:
LMIC_sendAlive();
Serial.println("EV_BEACON_FOUND");
break;
case EV_BEACON_MISSED:
Serial.println("EV_BEACON_MISSED");
break;
case EV_BEACON_TRACKED:
Serial.println("EV_BEACON_TRACKED");
break;
case EV_JOINING:
Serial.println("EV_JOINING");
break;
case EV_JOINED:
LMIC_setPingable(1);
Serial.print("SCANNING...\r\n");
//Serial.println("EV_JOINED");
break;
case EV_RFU1:
Serial.println("EV_RFU1");
break;
case EV_JOIN_FAILED:
Serial.println("EV_JOIN_FAILED");
break;
case EV_REJOIN_FAILED:
Serial.println("EV_REJOIN_FAILED");
break;
case EV_TXCOMPLETE:
Serial.println("EV_TXCOMPLETE (includes waiting for RX windows)");
Serial.print("LMIC.dataLen(EV_TXCOMPLETE): ");
Serial.println(LMIC.dataLen);
if(LMIC.dataLen) { // This code has not print the wrods, it
** may be cannot downlink.**
** // data received in rx slot after tx**
** Serial.print("Data Received: ");**
** Serial.write(LMIC.frame+LMIC.dataBeg, LMIC.dataLen);**
** Serial.println();**
** while(1) {**
}
}

Why is it that every newbie needs to be directed to the guides at the top of the first page. Is reading beneath you? At least you got the error highlighted, that's a start. You ask for help, try and make it easy for someone to try. Post your code inside tags so it's easy to select/copy/paste. We do do more that just look at it.

Does your sketch output this?

EV_TXCOMPLETE (includes waiting for RX windows)
LMIC.dataLen(EV_TXCOMPLETE): 0