UDP send and receive

Hello All,
I am working on programming my RV50 to be able to receive a message from a server then do some stuff if the message is ‘s’ , meanwhile, I won’t my RV50 to send back an “Ack” if the message was received accurately. I am able to receive the message but after nearly trying every thing I can, I am not receiving any thing on the website side, here is my code :
CadUDPSocketIN = assert(socket.udp())
assert(CadUDPSocketIN:setsockname(“”, 3033))

while true do
datain = CadUDPSocketIN:receive()
if(datain) then

    if (datain == 's') then  
       --Do something
       local  ip1, port1 = CadUDPSocketIN:getpeername()
       udp_c = assert(socket.udp())
       assert(udp_c:setpeername(ip1, port1))


Thanks for any help.