It would be best if you post simplified code and data that still exhibits the problem.
Boil the problem down to simplified code and you will likely find an answer comes quickly.
If you are accessing data with HTTPService, WebService, or RemoteObject, don't forget that Flex is asynchronous, so you can't send a data request and have other parts of the program that depend on the data already having been returned. That often means you need to call a function inside the result handler for the data service result event, after the data has been successfully processed.
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Attache code for Application. There is a reference there