To test the connection I used the standard example:arduino_input.
It runs well:
  Stable Library
  =========================================
  Native lib Version = RXTX-2.1-7
  Java lib Version   = RXTX-2.1-7
and the window with the rectangles pops up.
But when I connect 5V to Digital-input 5 (or any other) on the arduino - no response in processing.

What is wrong?
Do I have to implement on Arduino any special function/libaries?
(Arduino is working correctly, I have uploaded a programm that sends with Serial.println the input data)

I am using Processing 1.5.1
Arduina Ethernet + Arduino USB2Serial port