Flex HTTPService security error using Safari

I'm using the HTTPService object in actionscript to send some data to a php file on another server which then inserts the data to a database. I set up the crossdomain.xml file in the root of the directory that contains the php file to get around any security i开发者_如何学JAVAssues.

Everything works fine on Firfox 3.5 (on mac and pc) and on IE 7 & 8. When testing on Safari 4 I get an error which would be expected when a crossdomain.xml doesn't exist.

[RPC Fault faultString="Security error accessing url" faultCode="Channel.Security.Error" faultDetail="Destination: DefaultHTTP"] at mx.rpc::AbstractInvoker/http://www.adobe.com/2006/flex/mx/internal::faultHandler() at mx.rpc::Responder/fault() at mx.rpc::AsyncRequest/fault() at DirectHTTPMessageResponder/securityErrorHandler() at flash.events::EventDispatcher/dispatchEventFunction() at flash.events::EventDispatcher/dispatchEvent() at flash.net::URLLoader/redirectEvent()

Any ideas on how to get this to work on Safari? It's seems as if Safari isn't accessing the crossdomain.xml file.