ofxTCPClient first receive() always empty


I’m playing around with sending stuff with sockets and I’m encountering a problem with OF.
When calling receive(), receiveRaw or receiveRawBytes, the first call always returns empty. Am I doing something wrong?

I started out doing a server and client in python to get the hang of sockets and now I’m moving the client over to OF. I’ve still got the server in python and run it on the same computer to keep things simple.

This is my “client” code (of):

void ofApp::keyReleased(int key){
    //Open a a socket and try to receive some data
    cout << "ofApp::keyReleased(),    Start receiving" << endl;

    ofxTCPClient client_socket;
    client_socket.setup(ADDRESS, PORT);
    if (client_socket.isConnected()) {
        const int bufsize = 100;    //size of buffer to hold data
        char thedata[bufsize];        //buffer to hold received data

        // initialize buffer to all x's, to easily see if it's been overwritten
        for (int i = 0; i < bufsize; i++) {
            thedata[i] = 'x';

        //Print the buffer before receive
        cout << "thedata:";
        cout << "\n------------------------------\n";
        for (int i = 0; i < bufsize; i++) {
            cout << thedata[i];
        cout << "\n------------------------------\n";

        // Read in data from the socket
        client_socket.receiveRawBytes(thedata, bufsize);

        //Print the buffer after receive
        cout << "thedata:";
        cout << "\n------------------------------\n";
        for (int i = 0; i < bufsize; i++) {
            cout << thedata[i];
        cout << "\n------------------------------\n";

        // Cleanup
        cout << "Closing socket" << endl;

And this is my “Server” code (python):

### Send stuff like files for example ###
import io
import socket

# Vars
ADDRESS = 'localhost'
SOCKET = 8001

# Start socket listening for connections
print "Start Server"
server_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
server_socket.bind((ADDRESS, SOCKET))
print "Waiting for Connection"
connection = server_socket.accept()[0] #returns a tupple with connection first
print "Connection accepted"

# Try to send stuff
print "Start sending"

theFile=open('test_send.jpg', 'rb')
#theFile=open('test_send.txt', 'rb')
print theFile
MESSAGE = theFile.read()
MESSAGE = "Hello world dfs!"  #uncomment to just send a string

sent = connection.send(MESSAGE)
print "sent:"
print sent
print "Sending finished"

# cleanup