problem with sending data through non-blocking socket

Please help me with problem. I want to program Ftp client. I use non-blocking socket.
The initial settings of the socket and connect to Ftp are shown below.

SOCKET make_socket_ftp(const IPN ip, int port, int tm_conn)

{
    SOCKET newSocket = INVALID_SOCKET;
    int operationResult;
    struct sockaddr_in serverAddr;
    int addrLen;
    bzero(&serverAddr, sizeof(serverAddr));
    newSocket = socket(AF_INET, SOCK_STREAM, 0);
    if (newSocket != INVALID_SOCKET)
    {
        serverAddr.sin_family = AF_INET;
        serverAddr.sin_addr.s_addr = ip;
        serverAddr.sin_port = htons(port);
        addrLen = sizeof(serverAddr);
	int blockingState = 0;
	operationResult = setsockopt(newSocket, SOL_SOCKET, SO_BLOCKING, &blockingState, sizeof( blockingState));
	if (operationResult == 0 ) //success setsockopt
	{
	    operationResult = connect(newSocket, (PSA) &serverAddr, addrLen);
	    if (operationResult == 0) //success connect
	    {
	        return (newSocket);   
	    }
	    if (fdError() == EINPROGRESS)
	    {
	        fd_set wrsd;
	        struct timeval tv;
	        int maxfd = 2;

	        FD_ZERO(&wrsd);
	        FD_SET(newSocket, &wrsd);
	        tv.tv_sec = tm_conn;
	        tv.tv_usec = 0;
	        operationResult = fdSelect(maxfd, NULL, &wrsd, NULL, &tv );
	        if (operationResult > 0)
	        {
	            int err, lenErr;
		    lenErr = sizeof(err);
		    operationResult = getsockopt(newSocket, SOL_SOCKET, SO_ERROR, &err, &lenErr);
		    if ((operationResult == 0) && // success getsockopt
		       (err == 0))
		    {
		        return newSocket;
		    }
		 }
             }
         }
     }
     if (newSocket != INVALID_SOCKET)
         fdClose(newSocket);
     return (INVALID_SOCKET);
}

function for receiving data through socket here:

int readSocketData(SOCKET socket, char *buf, int sizeBuf, int timeoutValSec)
{
    fd_set rdsd;
    int operationResult;
    struct timeval tv;

    operationResult = recv(socket, buf, sizeBuf, 0);
    if (operationResult >= 0)
    	return(operationResult);
    if (fdError() == EWOULDBLOCK)
    {
    	int maxfd = 2;
	FD_ZERO(&rdsd);
	FD_SET(socket, &rdsd);
	tv.tv_sec = timeoutValSec;
	tv.tv_usec = 0;
	operationResult = fdSelect(maxfd, &rdsd, NULL, NULL, &tv);
	if (operationResult > 0)
	{
	    operationResult = recv(socket, buf, sizeBuf, 0);
	    if (operationResult >= 0)
		return(operationResult);
	}
    }
    return(-1);
}

function for sending data here:

int writeSocketData(SOCKET socket, char *buf, int sizeBuf, int timeoutValSec)
{
    fd_set wrsd;
    int operationResult;
    struct timeval tv;

    operationResult = send(socket, buf, sizeBuf, MSG_DONTWAIT);
    if (operationResult >= 0)
    {
    	printf("sended %d bytes\n", operationResult);
    	return (operationResult);
    }
    if (fdError() == EWOULDBLOCK)
    {
    	int maxfd = 2;
	FD_ZERO(&wrsd);
	FD_SET(socket, &wrsd);
	tv.tv_sec = timeoutValSec;
	tv.tv_usec = 0;
	operationResult = fdSelect(maxfd, NULL, &wrsd, NULL, &tv );
	if(operationResult > 0)
	{
		operationResult = send(socket, buf, sizeBuf, 0);
		if(operationResult >= 0)
		{
			error = 0;
			setsockopt(socket, SOL_SOCKET, SO_BLOCKING, &error, err_len );
			return (operationResult);
		}
	}
    } else
    {
	printf("error in write data to socket");
    }
    return (-1);
}

Connection to the server and receiving welcome message are occured successfully. And then when I sent request for login ftp (ex. "USER mc\n") to external FTP server, data don't come to server and in console I had retransmit timeout. If I send request to local server, I don't have this problem.The difference between the external and local server consists only in varying workload.

What could be the reason?