RN2483 Downlink

Hi Guys,

My downlink developements with the RN2483 progress step by step.
Today it works with a Kerlink iFemtoCell Gateway.
But i would like to use the confirmation of the confirmed downlink messages.

So i send a JSON over MQTT from a java MMI.
When i check the SPF and the Gateways Logs, it seems the ack is received by Lora Server but the ack frames which is sent over MQTT contains a nack.

For example :

I used the Class C on Lora Server and on the RN2483. The Time Out is 30sec.
The frame is received on the RN2483.

I don’t understand why “acknowledged is false”.
The Automatic Reply is enabled on the RN2483. It seems there are no retries, so the lora server get the Ack from the node or not ?