Issue
The Flash onload method does not function correctly from within Director. When this function is executed, it should pass a boolean (success) value of True or False.

If the file specified by the "load" event method is missing or the URL is incorrect, no value will be passed. ( a value (success) of False should be passed)

Example:

XMLObj=newObject("XML")
setCallback(XMLObj, "onLoad", #loadMyXML, 0)
XMLObj.load("http://some incorrect URL")


on loadMyXML me, arg1, success
  if success = TRUE then
    go to frame 3
    put "XML loaded="&success
  end if
end loadMyXML 

Reason
This is due to a bug in the Flash Asset Xtra that prevents a "missing file" error from being forwarded to the Flash XML object. Therefore, the onLoad callback handler never gets called if an XML file [being referred to by a Flash XML load object] is missing. The Director engineering team is aware of this outstanding bug and is actively working to resolve it. Please return to this TechNote for further updates.

Workaround
Use the preLoadNetThing function to check that the XML file exists prior to running an ActionScript load event. PreLoadNetThing will download a file to the local cache so it can be used later without a download delay. It also returns a network ID value that can be used with the Lingo functions netDone() and netError() to monitor the progress of the preLoadNetThing operation.

One issue to consider is that the netDone() and netError() functions need to be checked because they do not broadcast their results. The generally accepted method used is to check netDone() and netError() in consecutive frames following the initial preLoadNetThing function. Use of preLoadNetThing is discussed and demonstrated in the Director Sample movie How do I use preLoadNetThing ? (TechNote 14595).

The method described in this TechNote involves creating a small 4 frame Director movie that will run prior to the main movie. This small movie will contain a Flash object which checks to see if the XML file exists. If the file exists and downloads without an error, then the "main" movie that hosts the Flash XML object opens. If these is an error, an error message is presented.

Additional information
The following Technotes include sample movies that use onload callback with a Flash Objects and XML:

XML Xtra parser memory leak issue (TechNote 16805)
Global Flash command for creating an ActionScript object (TechNote 16691)