I have a communication problem with proccesing and arduino

when I try to run the basic program in Arduino library with proccesing I get this error:

Display 0 does not exist, using the default display instead.

WARNING:  RXTX Version mismatch

                Jar version = RXTX-2.2pre1

                native lib Version = RXTX-2.2pre2

this is the program

import processing.serial.*;
import cc.arduino.*;

Arduino arduino;
int ledPin = 13;

void setup()
{
  //println(Arduino.list());
  arduino = new Arduino(this, Arduino.list()[0], 57600);
  arduino.pinMode(ledPin, Arduino.OUTPUT);
}

void draw()
{
  arduino.digitalWrite(ledPin, Arduino.HIGH);
  delay(1000);
  arduino.digitalWrite(ledPin, Arduino.LOW);
  delay(1000);
}

hi i am new in procesing
I'm trying to do a very simple program with an arc
 the arc is basically increase and decrease with the arrow keys
the problem is
 when I  click play the arc increases and you can see it  increasing
  but there is no decrease in the image

float x1= 270.0;
void setup() {
size(480, 420);

}
void draw() {
if (keyPressed && (key == CODED)) { // If it’s a coded key


if (keyCode == LEFT) { // If it’s the left arrow
x1--;
} else if (keyCode == RIGHT) { // If it’s the right arrow
x1++;
}
}

println(x1);
fill(102);
smooth();
arc(190, 60, 80, 80, radians(x1), TWO_PI);


 
}