LoraWan Server not resend or notify error when sending downlink

Hi, i am implement lorawan network on RPi3+ with RAK831 gateway
My issue is when i send downlink packet by using restAPI/WebAPI, i don’t see the confirmation or error about the downlink! In Lorawan Frame, server only send the downlink one time. I sure that the node do not recieve any data because i unplugged it from the batterry! and the node is at Class C

What is wrong with my local server? Or i configured something so stupid?? The uplink is so okay but only downlink have problem