White screen when loading swf in https

[Guest]

When loading in https, my swf flashes for split second and then it turns into a blank white screen. It seems the flash is loading while doing tihs. When the user manually press browser refresh button it will finally displays. What causes this?

To reproduce this issue, open https://www.vantagefx.com/webtrader in a clean browser environment to avoid browser caching (eg: Google Chrome Incognito mode)

The problem doesn't happen when the same swf is loaded via http, eg: http://www.enfinium.com.au/webtrader. (Those are same swf, only different branding)

Please help

[Guest]

Further investigation shows this problem is caused by following exceptions. Strangely only happen when swf is loaded via https. This exception happen when my preloader class dispatches the complete

event:

this.dispatchEvent(new Event(Event.COMPLETE));  

Is this a known issue? How can I fix / debug further the problem?

TypeError: Error #1009: Cannot access a property or method of a null object reference.

at mx.managers::SystemManager/http://www.adobe.com/2006/flex/mx/internal::rawChildren_removeChild()

at mx.managers::SystemChildrenList/removeChild()

at mx.managers::SystemManager/preloader_preloaderDoneHandler()

at flash.events::EventDispatcher/dispatchEventFunction()

at flash.events::EventDispatcher/dispatchEvent()

at mx.preloaders::Preloader/displayClassCompleteHandler()

at flash.events::EventDispatcher/dispatchEventFunction()

at flash.events::EventDispatcher/dispatchEvent()