Arduino Micro: cannot upload sketches

Hi, I've the following problem:
when I try to upload a sketch on Arduino Micro, the operation fails, with the following message:

Couldn’t find a Leonardo on the selected port. Check that you have the correct port selected. If it is correct, try pressing the board's reset button after initiating the upload.
at processing.app.debug.AvrdudeUploader.uploadViaBootloader(AvrdudeUploader.java:153)
at processing.app.debug.AvrdudeUploader.uploadUsingPreferences(AvrdudeUploader.java:67)
at processing.app.Sketch.upload(Sketch.java:1666)
at processing.app.Sketch.exportApplet(Sketch.java:1622)
at processing.app.Sketch.exportApplet(Sketch.java:1594)
at processing.app.Editor$DefaultExportHandler.run(Editor.java:2382)
at java.lang.Thread.run(Thread.java:745)

My system is Debian 8 Jessie, Arduino IDE is 1.0.6
Note that on bottom right corner of IDE I correctly see "Arduino Micro on /dev/ttyACM0"
Note even that USB cable I'm using is the same I use for debugging my Tablet, so I guess this is not a only-power USB cable.

Thanks

UPDATE 1: I tried on a windows system: the board is found and the sketch is correctly uploaded: the board is not defective.

UPDATE 2: I found on my Linux system that the Serial Port must be select any time through Tools->Serial Port: at each upload, the port number is automatically incremented by 1 and I have to manually flag it. For example now the port is /dev/ttyACM22!!!
In this case the TX RX leds blink when uploading, the IDE confirms that the sketch is uploaded neverthless the behaviour of the Arduino Micro does not change!