bugs in BC CRM web service need to be fix (Server was unable to process request ERROR: A server error has occured)

I'm using the following code to retrieve order list is working fine but it give me an error Server was unable to process request ERROR: A server error has occurred when I trying to retrieve order total paid with same code: and the output when retrieve order total paid is [object Object]

var wsUrl = "https://mysite.worldsecuresystems.com/CatalystWebService/CatalystCRMWebservice.asmx?WSDL";

                      var RetrieveTotalPaidXML =

                      '<?xml version="1.0" encoding="utf-8"?>\

                      <soap12:Envelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" \

xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:soap12="http://www.w3.org/2003/05/soap-envelope">\

                      <soap12:Body>\

                      <Order_RetrieveTotalPaid xmlns="http://tempuri.org/CatalystDeveloperService/CatalystCRMWebservice">\

                      <username>user</username>\

                      <password>pass</password>\

                      <siteid>111222</siteid>\

                      <orderId>112345</orderId>\

                      </Order_RetrieveTotalPaid>\

                      </soap12:Body>\

                      </soap12:Envelope>';

                       $.ajax({

                        type: "POST",

                        url: wsUrl,

                        Host: "mysite.worldsecuresystems.com",

                        contentType: "application/soap+xml; charset=utf-8",

                        data: RetrieveTotalPaidXML,

                        dataType: "xml",

                        success: processSuccess,

                        error: function(){alert("Error: Something went wrong");}

                        });       

                       function processSuccess(ResData) {

                       var RetrieveTotalPaidParse = $.parseXML(ResData);

                       var $xmlRetrieveTotalPaidParse = $(RetrieveTotalPaidParse);

                       var $Order_RetrieveTotalPaidResult = $xmlRetrieveTotalPaidParse.find('Order_RetrieveTotalPaidResult');

                               $Order_RetrieveTotalPaidResult = $(this).find('Order_RetrieveTotalPaidResult').text();

                               $('#RetrieveTotalPaidResult').text(Order_RetrieveTotalPaidResult);

                    }

I think there a bug in BC CRM Web Service when trying to make a request for Order_RetrieveTotalPaid using soap need to be fix