PostprocessBuildPlayer for Android under MacOSX

I'm using Unity3D 3.5.6f4 under OS X 10.8.2 and I'm building a project for the Android platform. I need to add some assets to the apk so I'm trying to use the PostprocessBuildPlayer in order to achieve this... now I'm not really familiar neither with PostprocessBuildPlayer nor with perl scripting, but I'm encountering this problem: the 2nd argument which should be the 'target platform' is reporting "Unsupported build target!". Obviusly I switched to the Android platform before building, and if I switch back to iOS platform then the argument say correctly "iOS".

Is there something that I'm missing?