XML : not able to make the xml request in soap php

Please help me to fix this SOAP Request issue. I am sending the values correctly through SOAP. but it shows below error.

I am trying to fix this issue last 10 days. but I couldn't fix. I can't find where the issue occur.

Please check my request header and SOAP Response.

getting error : HTTP/1.1 500 Internal Server Error. I am using PHP. But Response

X-AspNet-Version: 4.0.30319

X-Powered-By: ASP.NET

what will be the issue? pls reply me as soon as possible.

  My Code :  $SKUItem = array("SKU"=>"124050001","SKUID"=>"6750");   $SKUList = array("SKUItem"=>$SKUItem);   $values = array("SecurityCode"=>"ShootersWW54321","SKUList"=>$SKUList);  $soap_client = new SoapClient('http://brownellsservices.spintest.com/asmx/WS_Brownells_OrderV2.asmx?WSDL', array('exceptions' => 0));  $quote = $soap_client->GetSKUDetail($values);  print($quote);  print($quote->GetSKUDetailResult);    

I am getting following error:

    SoapFault exception: [soap:Server] System.Web.Services.Protocols.SoapException: Server was unable to process request. ---> System.NullReferenceException: Object reference not set to an instance of an object. at WS_Brownells_OrderV2.GetSKUDetail(SKUDetailRequest s) in D:\inetpub\userwebs\BrownellsServices\App_Code\WS_Brownells_OrderV2.vb:line 1371 --- End of inner exception stack trace --- in /var/www/clients/client3/web23/web/shooters/brownells/brownells.php:19 Stack trace: /var/www/clients/client3/web23/web/shooters/brownells/brownells.php(19): SoapClient->__call('GetSKUDetail', Array) /var/www/clients/client3/web23/web/shooters/brownells/brownells.php(19): {main}  help me to solve the problem.    

    REQUEST HEADER :-  POST /asmx/WS_Brownells_OrderV2.asmx HTTP/1.1  Host: brownellsservices.spintest.com  Connection: Keep-Alive  User-Agent: PHP-SOAP/5.3.3-7+squeeze15  Content-Type: text/xml; charset=utf-8  SOAPAction: "https://api.brownells.com/asmx/WS_Brownells_OrderV2.asmx/GetSKUDetail"  Content-Length: 258    
SOAP Response:  HTTP/1.1 500 Internal Server Error  Cache-Control: private  Content-Type: text/xml; charset=utf-8  Server: Microsoft-IIS/7.0  X-AspNet-Version: 4.0.30319  X-Powered-By: ASP.NET  Date: Sat, 22 Aug 2015 06:07:01 GMT  Content-Length: 709


soap:ServerSystem.Web.Services.Protocols.SoapException: Server was unable to process request. ---> System.NullReferenceException: Object reference not set to an instance of an object.     at WS_Brownells_OrderV2.GetSKUDetail(SKUDetailRequest s) in D:\inetpub\userwebs\BrownellsServices\App_Code\WS_Brownells_OrderV2.vb:line 1371     --- End of inner exception stack trace ---  

  

Thanks in ADVANCE. Please solve this issue.