[flexcoders] flash.system::Worker could not be found

[Csomák Gábor]

HI!
I'm trying to implement workers to an existing Flex/AIR project, but I get
the following runtime error:

VerifyError: Error #1014: Class flash.system::Worker could not be found.

at line:

var worker:Worker =
WorkerDomain.current.createWorker(Workers.TUtils_DataToXMLToFileWorker);


anybody got idea why it is?
thanks!