Strange problem with a soap request

here is the code:
function ConnectBySoap()
{
     SOAP.wireDump = "true";    
try     {    
var service = SOAP.connect("http://softwaretest/DocumentTrackingService/Service1.asmx?WSDL");
var DocumentID ={soapType: "xsd:string",soapValue:"Doc21"};
service.GetTrackingInfo(DocumentID);
        }    
catch(error)     {               }
}

Here is the debugger:
<?xml version="1.0" ?><SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/"><SOAP-ENV:Body><m:GetTrackingInfo xmlns:m="http://softwaretest/DocumentTrackingService" xmlns="http://softwaretest/DocumentTrackingService">Doc21</m:GetTrackingInfo></SOAP-ENV:Body></SOAP-ENV:Envelope>
<?xml version="1.0" encoding="utf-8"?>
<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <soap:Body>...

the big thing is  xmlns="http://softwaretest/DocumentTrackingService">Doc21</m:GetTrackingInfo>
Doc21 should be (correct me if I am wrong) in side an <string></string> set.