CC3220SF-LAUNCHXL: How to handle SL_SOCKET_TX_FAILED_EVENT?

Hi! The point is how to know what is the cause of the failed TX. As far as I understand that error is emitted when a sk_Send() fails, according to the header:

In case of transmission failure an async event SL_SOCKET_TX_FAILED_EVENT is going to be received.

but there are no information about the possible causes.
Anyway my use case is the following:

1. every X minutes the MCU wakes up
2. acquires data from sensors
3. send them using a GET HTTP request
4. hibernates for other X minutes

The GET HTTP request is done manually in this way:

// Retrieve ip from host name
sl_NetAppDnsGetHostByName()

// Open socket
sl_SetSockOpt()
sl_Connect()

// Send formatted GET request
sl_Send()

// Receive answer
sl_Recv()

// Close socket
sl_Close()

Furthermore, I'm asserting the ret code of sl_Send() but it doesn't return a negative value on failure. Then when I receive the async event I really don't know what specific sl_Send() command has failed:

_i16 HTTPClient_GET(char *service, char *header, char *data)
{
    _i16 ret;

    char requestheader[256];
    sprintf(requestheader, " %s\r\nUser-Agent: %s\r\nHost: %d.%d.%d.%d\r\n\r\n", HTTP_VERSION, HTTP_USERAGENT,
            (_u8)SL_IPV4_BYTE(HTTPClient.ipV4Addr.sin_addr.s_addr, 0),\
            (_u8)SL_IPV4_BYTE(HTTPClient.ipV4Addr.sin_addr.s_addr, 1),\
            (_u8)SL_IPV4_BYTE(HTTPClient.ipV4Addr.sin_addr.s_addr, 2),\
            (_u8)SL_IPV4_BYTE(HTTPClient.ipV4Addr.sin_addr.s_addr, 3));

    strcpy(HTTPClient.response.content, "");
    HTTPClient.response.contentLen = 0;
    HTTPClient.response.status = 0;

    _Write("GET ");
    _Write(service);
    _Write("?");
    _Write(header);
    _Write("&");
    _Write(data);
    ret = _Write(requestheader);

    UART_PRINT("[HTTP] HTTP GET Request sent\r\n");
    UART_PRINT("GET %s?%s&%s%s", service, header, data, requestheader);

    return ret;
}

_i16 _Write(char *data)
{
    _i16 ret;

    ret = sl_Send(HTTPClient.sockId, data, strlen(data), 0);
    ASSERT_ON_ERROR(ret);

    return ret;
}

For this reason I don't understand if I need to just retry sending data (i.e. ALL data was't transmitted) or I need to close and reopen the socket, and so on...