In order for Oracle APEX Flash Charts to work, you would need a crossdomain.xml file placed in the root folder of your virtualhost.
<?xml version="1.0"?>
<!DOCTYPE cross-domain-policy SYSTEM "http://www.macromedia.com/xml/dtds/cross-domain-policy.dtd">
<cross-domain-policy>
<allow-access-from domain="*" />
</cross-domain-policy>
For more details on how to have a stricter crossdomain policy, visit Adobe Developer Site .
But when you are using Apache2 as a reverse proxy, you could be having another problem.
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