Ethernet shield can't connect server with keep alive connection - arduino

Question

I want to use Ethernet shield to send/get data from my Apche server (localhost).
Ethernet(or Esp8266) ======(request.php by post method)==>>> server
Ethernet(or Esp8266) <<<=====(respond header and data)==== server
i send header to server to get data.
In my header:
If i use connection: close. This way seems ok. But when i use connection: keep-alive. it can't connect or get any data till connection time out.
This is my header and way to send my data to server:
String httpRequest(String data){
String result="";
if(client.connect(server, 80)){
Serial.println("connected");
client.println("POST /pihome1/getStatus.php HTTP/1.1");
client.println("Host: localhost");
client.println("Accept: *" "/" "*");
client.println("Content-Length: " + String(data.length()));
client.println("Content-Type: application/x-www-form-urlencoded");
client.println("Connection: keep-alive");
client.println();
client.print(data);
}
else {
//if you didn't get a connection to the server:
Serial.println("connection failed");
}
//Reading data
unsigned long start = millis();
int timeout = 2000;
while (millis() - start < timeout){
while (client.available()) {
char c = client.read();
result += c;
}
}
if (!client.connected()) {
Serial.println();
Serial.println("disconnecting.");
client.flush();
client.stop();
}
return result;
}
After the first success it can't connect till time out connect.
========Request to server=========
connected
HTTP/1.1 200 OK
Date: Sun, 04 Oct 2015 08:03:46 GMT
Server: Apache/2.4.4 (Win32) OpenSSL/0.9.8y PHP/5.4.16
X-Powered-By: PHP/5.4.16
Content-Length: 10
Keep-Alive: timeout=50, max=100
Connection: Keep-Alive
Content-Type: text/html
1&1eos
========End of request=========
========Request to server=========
connection failed
========End of request========
Please tell me what problems?