BlueSmirf and Adruino - TX seems not to be working
Ok I figured out. To those who will get into this kind of trouble, it was really the baudRate who was misconfigured into my bluetooth module. That explain why the transmission of data worked, not the reception.

The fact is I was changing the bluetooth Bps rate but not permanently, so when I was reading the bluetooth configuration it was actually diplaying the not permanently BaudRate. So typping the

SU, 96
in my bluetooth command mode resolved my issued. (My arduino was configured to send at 9600 too, of course).