I'm absolutely sure that you are using external data in your flash/flex applications. It is a good practice to transfer information in XML format. Most of the projects that I'm working on also use XML and in most of them I have a class that converts the data to JSON object. The problem with this workflow is that the parser's logic is always different because the XML is different. These days I wrote a class that solved this problem and directly converted every given XML file to a JSON object.
Ok, that was a long journey. I took an already build project and I had to make some changes. It's a complex system involving flex applications, nodejs and a mobile site. Before to start making changes I had to setup the project and make it work on my local machine. I spend few days doing this. At the end I successfully compile the flex application and made the necessary corrections. I uploaded the new swf file and of course it didn't work.