WWW class "couldn't connect to host"

After research, I decided to use PHP to send mail via Web player app, since you can't use System.net.mail on this platform.

On the php side, everything is fine, I use swift mailer and the gmail smtp. When the file is hosted and I call it via a browser it works fine & send the mails.

I host my web app on the same server, here's my C# code to call the php script :

public string phpUrl = "myAdress/sendMail.php";

    public void SendMail ()
    {
        StartCoroutine(loadPhpMail());
    }

    private IEnumerator loadPhpMail()
    {
        WWW postPhp = new WWW (phpUrl);
        yield return postPhp;

        if (postPhp.error != null)
        {
            Debug.Log("error : "+postPhp.error);
        }
        else
        {
            if (postPhp.text=="true")
            {
                Debug.Log("success");
            }
        }
    }

And the line "Debug.Log("error : "+postPhp.error);" returns "error : couldn't connect to host".

I did my research work, and couldn't find a workaround. I tried some things like add a crossdomain policy to the serv.

Thank's guys for reading this. Bye !