Soap Null Error

Question

The following response handled with the code below causes the error at the bottom when no records are in the response.
Is this a problem with the XML or the code?
How do I get around it?
Thanks
<?xml version="1.0" encoding="UTF-8"?>
<SOAP-ENV:Envelope
  SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"
  xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/"
  xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/"
  xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <SOAP-ENV:Body>
    <ns1:WbSc_Repr_RepairDetailResponse xmlns:ns1="http://www.4d.com/namespace/default">
      <RepairDetails xsi:type="xsd:anyType"/>
    </ns1:WbSc_Repr_RepairDetailResponse>
  </SOAP-ENV:Body>
</SOAP-ENV:Envelope>
protected function WbSc_Repr_RepairDetailResult_resultHandler(event:ResultEvent):void
                 if (event.result.RepairDetails is ArrayCollection){
                    repairDetails =  event.result.RepairDetails as ArrayCollection;
                } else
                    repairDetails =  new ArrayCollection([event.result.RepairDetails]);
ReferenceError: Error #1069: Property RepairDetails not found on String and there is no default value.
    at components::Onsite/WbSc_Repr_RepairDetailResult_resultHandler()
    at components::Onsite/__WbSc_Repr_RepairDetailResult_result()
    at flash.events::EventDispatcher/dispatchEventFunction()
    at flash.events::EventDispatcher/dispatchEvent()
    at mx.rpc::CallResponder/result()
    at mx.rpc::AsyncToken/http://www.adobe.com/2006/flex/mx/internal::applyResult()
    at mx.rpc.events::ResultEvent/http://www.adobe.com/2006/flex/mx/internal::callTokenResponders()
    at mx.rpc::AbstractOperation/http://www.adobe.com/2006/flex/mx/internal::dispatchRpcEvent()
    at mx.rpc::AbstractInvoker/http://www.adobe.com/2006/flex/mx/internal::resultHandler()
    at mx.rpc::Responder/result()
    at mx.rpc::AsyncRequest/acknowledge()
    at DirectHTTPMessageResponder/completeHandler()
    at flash.events::EventDispatcher/dispatchEventFunction()
    at flash.events::EventDispatcher/dispatchEvent()
    at flash.net::URLLoader/onComplete()

Answer 1

This is the response as shown in the raw view on the data service panel
<?xml version="1.0" encoding="UTF-8"?>
<SOAP-ENV:Envelope
  SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"
  xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/"
  xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/"
  xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <SOAP-ENV:Body>
    <ns1:WbSc_Repr_RepairDetailResponse xmlns:ns1="http://www.4d.com/namespace/default">
      <RepairDetails xsi:type="xsd:anyType"/>
    </ns1:WbSc_Repr_RepairDetailResponse>
  </SOAP-ENV:Body>
</SOAP-ENV:Envelope>
I only get the error on the first time when the response returns no records.
Been driving me crazy for a while now.