help with soap ui and pl sql

greetings to all.

  I'm trying to create a pl sql web service client to communicate with siebel. from soapui I connect with the siebe web service.

  (raw request)
POST http://172.21.100.8/eai_esn/start.swe?S ... ord=SADMIN HTTP/1.1
Content-Type: text/xml;charset=UTF-8
SOAPAction: "rpc/http://172.21.100.8/WebService/:Crear_Modificar_Medico"
User-Agent: Jakarta Commons-HttpClient/3.1
Host: 172.21.100.8
Content-Length: 1714


 

   
None     
Loginname     
Passwrd

 
     
        <_XML xsi:type="sh:CuerpoTopElmt" xmlns:sh="http://www.siebel.com/xml/SH%20Medico">
           
             
                  ?
                  ?
                  ?
                  ?
                  ?
                 
                  ?
                 
                  ?
                 
                  ?
                 
                  ?
             
           
       
     
 



  but from pl sql  I get a 500 error. wiht this code...


DECLARE

    req  UTL_HTTP.req := NULL;
    resp  UTL_HTTP.resp := NULL;
    respVal VARCHAR2(32000);
    reqXML VARCHAR2(32760);

BEGIN
reqXML := '
 

 
     
        <_XML xsi:type="sh:CuerpoTopElmt" xmlns:sh="http://www.siebel.com/xml/SH%20Medico">
           
             
                  ?
                  ?
                  ?
                  ?
                  ?
                 
                  ?
                 
                  ?
                 
                  ?
                 
                  ?
             
           
       
     
 
';

dbms_output.put_line('Length of Request:' || length(reqXML));
  dbms_output.put_line ('Request: ' || reqXML);



req := UTL_HTTP.begin_request('http://172.21.100.8/eai_esn/start.swe?SWEExtSource=WebService&SWEExtCmd=Execute&UserName=SADMIN&Password=SADMIN', 'POST',utl_http.HTTP_VERSION_1_1);


    UTL_HTTP.set_header(req, 'Content-Type', 'text/xml; charset=utf-8');/  UTL_HTTP.set_header(req, 'SOAPAction', '"rpc/http://172.21.100.8/WebService/:Crear_Modificar_Medico"');
UTL_HTTP.set_header(req, 'Content-Length', LENGTH(reqXML));
DBMS_OUTPUT.PUT_LINE('El contenido que enviamos es XML');    --UTL_HTTP.write_text(req, reqXML);    resp := UTL_HTTP.get_response(req);   
    dbms_output.put_line('Response Received');
  dbms_output.put_line('--------------------------');
  dbms_output.put_line ( 'Status code: ' || resp.status_code );
  dbms_output.put_line ( 'Reason phrase: ' || resp.reason_phrase );    UTL_HTTP.read_text(resp, respVal);
    UTL_HTTP.end_response(resp);
     
     
        DBMS_OUTPUT.PUT_LINE('******'||respVal||'******');

EXCEPTION
    WHEN UTL_HTTP.end_of_body THEN
      UTL_HTTP.end_response(resp);
END;

/


some vary can help me