flex HTTPService request error on iphone ios9 but ok in android and air

i used the HTTPService to get some text

it's ok in air and android and web but get Server.Error.Request in iphone ios9

how to deal ??? i spant 3 days do deal but not resolved

the wrong error code :

[IOErrorEvent type="ioError"

bubbles=false cancelable=false eventPhase=2

text="Error #2032: Stream Error.

URL:http://myserver/myproj/request_post2.php"

errorID=2032]

and get the null content .

the code is :

http_srv.send();

/////////////////////////////////////////////////////////////////////

<s:HTTPService id="http_srv"  resultFormat="text" fault="srv_faultHandler(event)" method="POST"

    result="srv_resultHandler(event)"  useProxy="false"

    url="http://myserver/myproj/request_post2.php"/>