[Editor] ImportPackage does not do its job

I compile every day my scene, and I launch Unity in command line, with a script of mine.
I need now to import packages. I have written in my editor script the following line :

AssetDatabase.ImportPackage(<full-path-of-package-to-import>,false);

In the editor log, the only traces I have are :

DisplayProgressbar: Decompressing
Refresh, detecting if any assets need to be imported or removed ... 0.026769 seconds (Nothing changed)
Updating ProjectSettings/ProjectSettings.asset - GUID: 00000000000000004000000000000000...
 done. [Time: 6.718502 ms] 

I seems that Unity sees the package, decompresses it, but does nothing more. No assets are imported.

I missed something ?
Of course, I have tried with several packages coming from the assetstore, with valid and invalid paths, …

Platform : Windows 7 + Unity 4.3.0f4

I also used the parameter “-importPackage” in command line, but I got 2 problems :

  • it seems it tries to import AFTER my script “-executeMethod”,
  • it reports an “Error while importing package: Package has unknown format”; of course, I can import same package manually… -

Any idea ???