Invalid XML generated from Flex WebService

I am trying to get Flex to communication with a Spring-WS webservice. But Flex generates a SOAP request that is not validated either by a PayloadValidatingInterceptor nor by soapUI. The problem seems to be related to the use of XML namespaces.

The not validated message looks like :

<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" >
  <soapenv:Header/>
  <soapenv:Body>
    <getAccountDataRequest xmlns="http://test.com/services/Account">
      <accountNumber>537048.001</accountNumber>
    </getAccountDataRequest>
  </soapenv:Body>
</soapenv:Envelope>

The 2 following variants are both validated :

<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap开发者_如何学Go.org/soap/envelope/" >
  <soapenv:Header/>
  <soapenv:Body>
    <ac:getAccountDataRequest xmlns:ac="http://test.com/services/Account">
      <accountNumber>537048.001</accountNumber>
    </ac:getAccountDataRequest>
  </soapenv:Body>
</soapenv:Envelope>

<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/"
                  xmlns:ac="http://test.com/services/Account">
  <soapenv:Header/>
  <soapenv:Body>
    <ac:getAccountDataRequest>
      <accountNumber>537048.001</accountNumber>
    </ac:getAccountDataRequest>
  </soapenv:Body>
</soapenv:Envelope>

From my understanding of the documentations I have read, the first version should be valid as well.

Is it Spring and soapUI that are too picky in what they accept ? Or is Flex generating invalid XML ?

Thanks for the help !

---

I finally added elementFormDefault="qualified" to the XSD defining my webservice, and now everybody agrees that the messages generated by Flex are correct.