As far as I can see the order of those elements should be irrelevant, so I'm not even sure why you would want a specific order.

Joost,
Here's the client code, where the messages are generated.

#!/usr/local/bin/perl
#CLIENT

use strict;
use warnings;

use SOAP::Lite +trace => qw(debug);
use MIME::Base64;

my $HOST = "http://localhost/perl/soap-dbi.pl";
my $NS = "urn:Delivery";
my $MsgHdr = "urn:MsgHeader";



#Data to be added to the request
my (@data) = (
              #Common MessageHeader
              SOAP::Data->name(MessageHeader => {
                                                
                                                 ( AgreementId => "urn
+:xxx-xxx:::" ),
                                                 ( ConversationId => "
+20050904-13:30:03.469-857" ),
                                                 ( Sequence => {
                                                                Id => 
+"What id is this",
                                                                Number
+ => "123",
                                                                Total 
+=> "6"
                                                               }
                                                 ),
                                                 ( Service => {
                                                               type =>
+ "service.type. What servicetype is this?"
                                                              }
                                                 ),
                                                 ( Action => "Problem 
+Submit" ),
                          ( MessageData => {
                                                                   Mes
+sageId => "20050904-13:30:03.469-8572\@xxx.xxx.xxx",
                                                                   Tim
+estamp => SOAP::Utils::format_datetime(localtime),
                                                                   Ref
+ToMessageId => "Which reference is this",
                                                                   Tim
+eToLive => SOAP::Utils::format_datetime(localtime)
                                                                  }
                                                 ),
                                                 
                                                 ( Description => "Thi
+s is the message header" ),
                          ( ErrorList => { Error => {
                                                                      
+      Description => "Error Description",                            
+                                                 codeContent => "code
+ content",                                                           
+                  errorCode => "Error Code",                         
+                                                    severity => "seve
+rity.type",                                                          
+                   location => "error location"                      
+                                                      }
                                                                }
                                                 ),
                                                 ( highestSeverity => 
+"severity.type" ),
                                                 ( id => "Which id is 
+this" )
                                                }
                              )->uri($MsgHdr)->prefix(''),

);
#Enable fault management globally
  use SOAP::Lite
    on_fault => sub { my($soap, $res) = @_;
      eval { die ref $res ? $res->faultstring : $soap->transport->stat
+us };
                      return ref $res ? $res : new SOAP::SOM;
    };


#print $soap->fault ? $soap->faultstring. "\n" : $soap->result;


my $soap = SOAP::Lite
        -> proxy($HOST)
        -> uri($NS);


#my $res = $soap->byName(@headers,@data);
my $res = $soap->GetbyName(@data);


#print $soap->retrieveDocument->result;
print $res->fault ? $res->faultstring. "\n" : $res->result;
[download]

Many thanks

The reason that the elements are not coming out in the order that you think you put them it, is that you are passing a hash reference as the second argument to SOAP::Data->name(), the elements in a hash are effectively in a random order which you cannot control. If you want more control over the structure of the generated XML you will need to explicitly create every element with SOAP::Data - you can find an example in Re: SOAP Beginner ... I hate to impose.

As to the question of why the elements need to be in a particular order, in general with XML this shouldn't matter but I have seen some XML parsers get upset about this when validating against a DTD, but you generally aren't doing this in a Web Service. If you (or the owner of the web service) care at all about interoperability, you will fix the server so that it behaves in an interoperable manner rather than hacking the client to work around it's quirks.

/J\