SOAP php非wsdl过程不存在

I have written web service in PHP. It has been working fine for couple of weeks. Today I had to change my SOAP client to be in non WSDL form, after making the following change, I am getting this annoying error:

Procedure 'FUNCTIONNAME' not present

My code:

//$client = new SoapClient("STWebServiceWSDL.wsdl", array('trace' => 1));
//This is working, but why, non wsdl below not working

$client = new SoapClient(null, array('location' => "https://mysite.com/STserver.php",
                                    'uri'      => "https://mysite.com/STserver.php",
                                    'trace'=>1));

Please help, I could not find any solution on the Net for the whole day.

My SOAP server is like this:

$server = new SoapServer("STWebServiceWSDL.wsdl");