Thank you PaulS, what i did:
The library folder "ros_lib" i copied into "user/sketchbook/libraries/", later, i open the file "ArduinoHardware.h" included in the "ros_lib" folder and a changed the following lines:
#include "Arduino.h"
//#include "WProgram.h"
and later, it works....
Problem solved..
Thank you for your help!!