soap-lite xmlns:order -> Registering namespaces with SOAP::Lite

So I would try

sub Submit {return (SOAP::Data->name('SubmitResponse')->type('xml') ->
+attr({'xmlns:order'="http://echo.nasa.gov/v9/order/fulfillment"})->va
+lue(ECHODataOrder::DataOrderRequest(@_)));}
[download]

Of course I would run it through perltidy first

sub Submit {
    return (
        SOAP::Data->name('SubmitResponse')->type('xml')->attr(
            { 'xmlns:order' = "http://echo.nasa.gov/v9/order/fulfillme
+nt" }
          )->value( ECHODataOrder::DataOrderRequest(@_) )
    );
}
[download]

I don't know much about XML/SOAP, but I don't think the part you're interested in ('xmlns:order') is called a prefix :)