Losing some socket packets from a Java server

Flash/AS3 client connected to Java server though sockets.

All the packets sent from the client to the server are recieved 100%,
but almost 10% of the packets sent from the server to the client are lost somewhere.

For example it will happen that Server sends message “Hello” to client 1 and client 2.
Client 1 recieves it but Client2 doesnt…

Do you think there is a problem in the “PrintWriter” to send the sockets out or in flash?