Crossdomain.xml file not being called by the SWF

Hi,

I'm serving an swf file compiled using flex builder 3.2 through plain HTTP, the SWF file calls a service in the same domain through HTTPS, as such, I put the following file in the root directory of my web server:

<?xml version="1.0"?>
<!DOCTYPE cross-domain-policy SYSTEM "http://www.adobe.com/xml/dtds/cross-domain-policy.dtd">
<cross-domain-policy>
    <allow-access-from domain="*" secure="false" />
</cross-domain-policy>

and name it crossdomain.xml

When the service is invoked, I get the following error: [RPC Fault faultString="Security error accessing url" faultCode="Channel.Security.Error" faultDetail="Destination: DefaultHTTP"]

When I check the access log files of my web server (Apache), there's no entry for crossdomain.xml (it is not being requested), why?

When I serve the SWF through HTTPs it works OK ... any ideas?

I have tried in several machines (different browsers, different versions of Flash player) and no success.