MQTT emqx downlink

Hi Guys me again,
Please help me I dont know waht happen with the downlink topic I ry to use this topic


but I don’t receive anithing
I Use emqx and the uplinks works perfect


you need to send a downlink below format

    "confirmed": true,                        // whether the payload must be sent as confirmed data down or not
    "fPort": 10,                              // FPort to use (must be > 0)
    "data": "AA=="                            // base64 encoded data (plaintext, will be encrypted by ChirpStack Network Server)

Thanks for your reply I try with the example and I have an txack
but not the downlink I don’t know why?

Did you send it on the correct fPort for your device?