I've just spend my complete afternoon in finding this error:
As you all may know in Actionscript classes you have to name the filename of a class the same as the class name:
For instance: MyService.as for class MyService
In php one is not obliged to do so, so myService.php for class MyService is not a problem.(Look at the uppercase character at the beginning of the class name).
Appearantly my mac local server doesnt mind differences in upper/lowercase characters, because the dataservice was working just fine.
But when copying my release build to the production server one service stopped working, since it didn't find the service file because of the namedifference (MyService.php - myService.php)
So to all ya php coders: keep the filename exactly the same as the class inside of it.