You have your phone still connected to your computer via USB ?

Yes always connected. 

Android version 2.3.4 

I'm having the same problem with an Android 2.3.5 device (Droid X2).  It has four USB modes, including:

Charge Only
PC Mode
Windows Media Sync
USB Mass Storage

 I know it has something to do with the device because the debug info appears when I connect other devices.  I can install the app in Charge Only mode and USB Mass Storage mode, but I'm just not getting debug feedback via the USB cable when I'm using the Droid X2.

Processing 2.0b8, MacOSX 10.6.8

even with the monitor of android sdk ?

How do I use the monitor?  I guess it's 64-bit.  My MacBookPro is 32-bit.  I'm getting an error message:

"You can't open the application monitor.app because it is not supported for this type of Mac"

But as I said, I can use the Processing IDE to get println() messages with my other phone, so it must be something specific to the device.