Failed Client-Socket Communication

I hve written a server program & a client program. The server is supposed to echo watever is typed in the client. I hve to get 16 values to be echoed. I hve created a string and all the values are added to this string. When I pass the string to the server, it doesn get echoed by the server. In fact server hangs @ tat part after establishing connection with the client. I am at my wits end!Can someone run the code for me & explain why it hangs when its supposed to echo the value in server? I hve changed my code 7 times already still I can't understand why it hangs, tis is really a desperate call, stuck with tis 4 4 days alreay.

SERVER PROGRAM:

[code] import java.io.*; import java.net.*; import java.util.*;

public class AS3{ public static void main(String[] args ){ int i = 1; try{ ServerSocket s = new ServerSocket(9001);

         for (;;){
             Socket incoming = s.accept( );
             System.out.println("Spawning " + i);
             new RealEchoHandler(incoming, i).start();
             i++;
         }
    } catch (Exception e){ System.out.println(e); }
}

}

class RealEchoHandler extends Thread{ DataInputStream in; DataOutputStream out; private Socket incoming; private int counter;

public RealEchoHandler(Socket i, int c){
    incoming = i;
    counter = c;
}

public void run(){
    try {

        in = new DataInputStream(incoming.getInputStream());
        out = new DataOutputStream(incoming.getOutputStream());

        boolean done = false;
        String str="";
        out.writeUTF("Connected!\n");
        out.flush();
        while (!done){
            out.writeUTF(">");
            out.flush();
            str = in.readUTF();
            System.out.println(in+":"+str);
            if (str == null)
                done = true;
            else{
                out.writeUTF("Echo (" + counter + "): " + str+"\n");
                out.flush();
            }
        }

        incoming.close();
     } catch (Exception e){
         System.out.println(e);
     }
}

}[/code]

CLIENT: [code] import java.io.*; import java.net.*; import java.util.*; class Client3{ public static void main(String[] args) { String store=""; String clientCar=""; String clientBranch=""; String clientDriver=""; String clientPasswd="";

    DataOutputStream out;
    DataInputStream in;
    try {
        Socket t = new Socket("127.0.0.1", 9001);

        in = new DataInputStream(t.getInputStream());
        out = new DataOutputStream(t.getOutputStream());
        BufferedReader br = new BufferedReader
                 (new InputStreamReader(System.in));
        boolean more = true;
        System.out.println(in.readUTF());
        while (more) {
            clientCar = in.readUTF();
            clientBranch = in.readUTF();
            clientDriver = in.readUTF();
            clientPasswd = in.readUTF();
            store = store + clientCar+clientBranch+clientDriver+clientPasswd;

            out.flush();
            store = in.readUTF();
            if (store == null)
                more = false;
            else
                out.writeUTF(store + "\n");
        }

     } catch(IOException e){
            System.out.println("Error" + e);
     }
     System.out.println(store);
 }

} [/code]