https://issues.sonatype.org/browse/FLEXMOJOS-381
You could be using an old version. It used to work in FM3. The link they put in the comments is completely irrelevant to the problem. The ticket is closed, but functionality doesn't exist any more. Or, to be precise, the last time I tried. It's not the only one though. Things get tougher once you want to run compc. I recall that it couldn't pick classes to compile, neither manifest etc. Best. wvxvw
