SoapFault exception - php

Question

I'm using PHP Version 5.4.16
When I make a SOAP call, it gives me error:
SoapFault exception: [soap:Server] Server was unable to process request. ---> Object reference not set to an instance of an object. in /var/www/html/VAS_sms/index.php:24
Stack trace:
#0 /var/www/html/VAS_sms/index.php(24): SoapClient->__call('SendSMS', Array)
#1 /var/www/html/VAS_sms/index.php(24): SoapClient->SendSMS(Array)
#2 {main}
That's beside a Warning:
Warning: The use statement with non-compound name 'SoapClient' has no
effect in C:\wamp\www\VAS_sms\index.php on line 2
I lost my mind making it run..
Here's my code:
<?php
use SoapClient;
ini_set("soap.wsdl_cache_enabled", "0"); // disabling WSDL cache
$wsdl_path = "https://smsvas.vlserv.com/KannelSending/service.asmx?WSDL";
$client = new SoapClient($wsdl_path, array('trace' => 1));
$userName = "username";
$Password = "password";
$SMSText = "text";
$SMSLang = "e";
$SMSSender = "sender";
$SMSReceiver = "01xxxxxxxxx";
try {
echo "<pre>\n";
$result = $client->SendSMS(array(
"Username" => $userName,
"Password" => $Password,
"SMSText" => $SMSText,
"SMSLang" => $SMSLang,
"SMSSender" => $SMSSender,
"SMSReceiver" => $SMSReceiver));
function objectToArray($d){
if (is_object($d)){
$d = get_object_vars($d);
}
if (is_array($d)){
return array_map(__FUNCTION__, $d);
}
else {return $d;}
}
$response_arr = objectToArray($result);
echo "return_code= " . str_replace(";", "", $response_arr);
echo "\n</pre>";
}
catch (SoapFault $exception) {
echo $exception;
}
?>
Any suggestions?
side Q: is there any file missing I should include instead of use SoapClient; ?!
Thanks in advance
EDIT 1
in the documentation file:
<?php
use SoapClient;
$client = new SoapClient("https://smsvas.vlserv.com/KannelSending/service.asmx");
$userName = "username";
$Password = "password";
$SMSText = "text";
$SMSLang = "e";
$SMSSender = "sender";
$SMSReceiver = "01xxxxxxxxx";
$result = $client->SendSMS(array(
"Username" => $userName,
"Password" => $Password,
"SMSText" => $SMSText,
"SMSLang" => $SMSLang,
"SMSSender" => $SMSSender,
"SMSReceiver" => $SMSReceiver));
$response_arr = objectToArray($result);
echo "return_code= " . str_replace(";", "", $response_arr);
function objectToArray($d)
{
if (is_object($d))
{$d = get_object_vars($d);}
if (is_array($d))
{return array_map(__FUNCTION__, $d);}
else {return $d;}
}
?>
Note:  We’re using PHP SoapClient to call the API Web Service, so you
need to enable the libxml PHP extension.  As its response is an
object (not string) so you need to convert it to an array by using
objectToArray function.