I use basic SOAP::Data on SOAP-server:

package AnPackage;
use vars qw(@ISA);
@ISA = qw(Exporter SOAP::Server::Parameters);

sub createRequestRequest {
 my $self          = shift;
 my $envelope      = pop;
 my @RequestParams = $envelope->paramsin;
 my $RequestNumber = "1-13";
 return SOAP::Data->name('createRequestResponse')->value(
   SOAP::Data->name( 'requestNumber' => $RequestNumber)
   );
}
1;
__END__
[download]

It is not help me(:
In output:
<?xml version="1.0" encoding="UTF-8"?><soap:Envelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:soapenc="http://schemas.xmlsoap.org/soap/encoding/" xmlns:xsd="http://www.w3.org/2001/XMLSchema" soap:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/"><soap:Body><createRequestRequestResponse xmlns="http://localhost/AnPackage"><requestNumber xsi:type="xsd:string">1-13</requestNumber></createRequestRequestResponse></soap:Body></soap:Envelope>
problem: exists<<<<xsi:type="xsd:string">>>>
I test this:

 return SOAP::Data->name('createRequestResponse')->type(undef)->value(
     SOAP::Data->name('requestNumber')->type(undef)->value($RequestNum
+ber)
    );
[download]

but this is not decide problem...