Arduino to Xively JSON Error 400 The Feed is Empty - json

Question

I am trying to upload data from an Aurdino to Xively. I can connect to Xively and even get the PUT request showing up on the Xively Request Log.
But i get the error 400 Bad Request
{"title":"JSON Parser Error","errors":"The feed is empty"}
I think the problem may be here
data = data + "\n" + "{\"version\":\"1.0.0\",\"datastreams\" : [ {\"id\" : \"Reading\",\"current_value\" : \"" + String(reading) + "\"}]}";
Any tips would be much appreciated.
Cheers and thanks
///////////////////////
// Saving to Xively ///
///////////////////////
int savetoxively(String reading, char* feedID) {
//getting the IP address for the xively website.
ip = 0;
Serial.print(WEBSITE); Serial.print(F(" -> "));
while (ip == 0) {
if (! cc3000.getHostByName(WEBSITE, &ip)) {
Serial.println(F("Couldn't resolve!"));
}
delay(500);
}
cc3000.printIPdotsRev(ip);
// formatting the data for the xively website.
int length = 0;
String data = ""; //the problem might be here, the serial monitor says the length is 0. should have something ing it.
data = data + "\n" + "{\"version\":\"1.0.0\",\"datastreams\" : [ {\"id\" : \"Reading\",\"current_value\" : \"" + String(reading) + "\"}]}";
length = data.length();
Serial.print("Data length");
Serial.println(length);
Serial.println();
// Print request for debug purposes
Serial.print("PUT /v2/feeds/");
Serial.print(feedID); //serial monitor shows the correct feedID here
Serial.println(".json HTTP/1.1");
Serial.println("Host: api.xively.com");
Serial.print("X-ApiKey: ");
Serial.println(API_key); //serial monitor shows the correct API key
Serial.print("Content-Length: ");
Serial.println(length, DEC);
Serial.print("Connection: close");
Serial.println();
Serial.print("Reading: ");
Serial.println(reading); //serial monitor shows the correct reading
Serial.println();
// connecting with the xively server
Adafruit_CC3000_Client client = cc3000.connectTCP(ip, 80);
if (client.connected()) {
Serial.println("Connected!");
Serial.print("feedID: ");
Serial.println(feedID);
client.print("PUT /v2/feeds/");
client.print(feedID);
client.println(".json HTTP/1.1");
client.println("Host: api.xively.com");
client.print("X-ApiKey: ");
client.println(API_key);
client.print("User-Agent: ");
client.println(USERAGENT);
client.print("Content-Length: ");
client.println(length);
client.print("Connection: close");
client.println();
client.print(data);
client.println();
Serial.println("data sent");
}
while (client.connected()) { //printing connection status
while (client.available()) { //HTTP/1.1 400 Bad Request
char c = client.read(); //Date: Sat, 15 Mar 2014 19:33:38 GMT
Serial.print(c); //Content-Type: application/json; charset=utf-8
//Content-Length: 58
//Connection: close
//X-Request-Id: f48494a26daa2a5f0979dc4460264d233103f0f5
//{"title":"JSON Parser Error","errors":"The feed is empty"}
}
}
client.close(); // closes the connection with xively
cc3000.disconnect(); //disconnects the Wifi network
return 1;
}