I just took over a clients flex project and I can't get the app to reflect even a simple trace statement. Before I took over, the project was last successfully built using the Flash Builder Beta 2 environment/sdk. I have the latest release version of Flash Builder 4. Upon importing the project into FB4, I got a ton of errors. Most of them mostly because of the changes made to the sdk from beta2 to release. Some of the things I corrected: - mx namespace from library://ns.adobe.com/flex/halo to library://ns.adobe.com/flex/mx - video player skinning: a lot of the state names for the video player component had been changed, more required states had been added. also there were other video related component and property names that had to be updated. But I fixed all that and the application was finally able to compile (although with some warnings mostly of the duplicate variable type) The only thing now is that whatever change I make to the project doesn't get reflected in the build (debug or release). I changed existing traces, added additional traces. Nothing shows up. I even removed the applicationComplete property in the main.mxml. Everything still ran like nothing changed. Also I can't seem to debug the app. Whenever I try to debug.. flash builder says.. "Swf Application doesn't contain the required debugging information ... " Anyone have any idea how I need to even begin tackling all this? Any help or pointers would be greatly appreciated.