Can't send data to Xively through Arduino Wi-Fi Shield, sending just one stream

I'm doing a project involving uploading data wirelessly, from an analog sensor. In this case it is a light sensor.

I am using an Arduino Uno R2, and an official Arduino Wi-Fi Shield. Below is my code:

#include <SPI.h>
#include <WiFi.h>
#include <HttpClient.h>
#include <Xively.h>

char ssid[] = "Bradley's MacBook Pro"; //  your network SSID (name) 

int status = WL_IDLE_STATUS;

// Your Xively key to let you upload data
char xivelyKey[] = "SOP7lASYJVcRecV98zlHosDc9nLIAXqnDnIxRnXAmNeKorIk";

// Analog pin which we monitor (0 and 1 are used by the Ethernet shield)
int sensorPin = 2;

// Define the strings for our datastream IDs
char sensorId[] = "light";
XivelyDatastream datastreams[] = {
  XivelyDatastream(sensorId, strlen(sensorId), DATASTREAM_FLOAT),
};
// Finally, wrap the datastreams into a feed
XivelyFeed feed(1125419529, datastreams, 1 /* number of datastreams */);

WiFiClient client;
XivelyClient xivelyclient(client);

void printWifiStatus() {
  // print the SSID of the network you're attached to:
  Serial.print("SSID: ");
  Serial.println(WiFi.SSID());

  // print your WiFi shield's IP address:
  IPAddress ip = WiFi.localIP();
  Serial.print("IP Address: ");
  Serial.println(ip);

  // print the received signal strength:
  long rssi = WiFi.RSSI();
  Serial.print("signal strength (RSSI):");
  Serial.print(rssi);
  Serial.println(" dBm");
}
void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);

  Serial.println("Starting single datastream upload to Xively...");
  Serial.println();

  // attempt to connect to Wifi network:
  while ( status != WL_CONNECTED) { 
    Serial.print("Attempting to connect to SSID: ");
    Serial.println(ssid);
    status = WiFi.begin(ssid);
    // wait 10 seconds for connection:
    delay(10000);
  } 
  Serial.println("Connected to wifi");
  printWifiStatus();
}

void loop() {
  int sensorValue = analogRead(sensorPin);
  datastreams[0].setFloat(sensorValue);

  Serial.print("Read sensor value ");
  Serial.println(datastreams[0].getFloat());

  Serial.println("Uploading it to Xively");
  int ret = xivelyclient.put(feed, xivelyKey);
  Serial.print("xivelyclient.put returned ");
  Serial.println(ret);

  Serial.println();
  delay(15000);
}

However unfortunately every time I get this back in serial:

Attempting to connect to SSID: Bradley's MacBook Pro
Connected to wifi
SSID: Bradley's MacBook Pro
IP Address: 10.0.2.3
signal strength (RSSI):-20 dBm
Read sensor value 1023.00
Uploading it to Xively
xivelyclient.put returned -1

Read sensor value 1023.00
Uploading it to Xively
xivelyclient.put returned -1

Read sensor value 684.00
Uploading it to Xively
xivelyclient.put returned -1

Read sensor value 684.00
Uploading it to Xively
xivelyclient.put returned -1

Read sensor value 684.00
Uploading it to Xively
No Socket available
xivelyclient.put returned -1

Read sensor value 684.00
Uploading it to Xively
No Socket available
xivelyclient.put returned -1

I noticed that after a few attempted it started to say No Socket available.

Does anyone have any clues as to where I've gone wrong?

I have resolved this problem. The issue is that I was using Arduino IDE 1.0.5 and there is a bug in that which prevents Wi-Fi communication. I have now changed to using an earlier IDE 1.0.2 and everything is running perfectly.