Java - Imprimir mediante robot

Buenas tardes estoy trabajando en Web Dynpro y estoy tratando de imprimir el documento html pero parece ser que no funciona el siguiente código y no lanza ningún tipo de excepción si se la pongo. Alguien me podria decir a qeu se debe tratar que no haga nada?

Gracias

public void onActionPrintEncuestaPDF(com.sap.tc.webdynpro.progmodel.api.IWDCustomEvent wdEvent )
{
//@@begin onActionPrintEncuestaPDF(ServerEvent)
try{
Robot robot = new Robot();


// Ctrl+P
//robot.keyPress(KeyEvent.VK_CONTROL );
//robot.keyPress(KeyEvent.VK_P );
robot.keyRelease(KeyEvent.VK_WINDOWS);
//robot.keyRelease(KeyEvent.VK_P );

/*Thread.sleep(500);

//Alt+U
robot.keyPress(KeyEvent.VK_ALT );
robot.keyPress(KeyEvent.VK_U );
robot.keyRelease(KeyEvent.VK_ALT );
robot.keyRelease(KeyEvent.VK_U );

Thread.sleep(500);

//entrée
robot.keyPress(KeyEvent.VK_ENTER);
robot.keyRelease(KeyEvent.VK_ENTER );

Thread.sleep(500);

//Alt+D+N
robot.keyPress(KeyEvent.VK_ALT );
robot.keyPress(KeyEvent.VK_D );
robot.keyPress(KeyEvent.VK_U );
robot.keyRelease(KeyEvent.VK_ALT );
robot.keyRelease(KeyEvent.VK_D );
robot.keyRelease(KeyEvent.VK_U );

Thread.sleep(500);*/
}
catch(Exception e){ }

//@@end
}

public void onActionPrintEncuestaPDF(com.sap.tc.webdynpro.progmodel.api.IWDCustomEvent wdEvent )
{
//@@begin onActionPrintEncuestaPDF(ServerEvent)
try{
Robot robot = new Robot();

// Ctrl+P
robot.keyPress(KeyEvent.VK_CONTROL );
robot.keyPress(KeyEvent.VK_P );
robot.keyRelease(KeyEvent.VK_CONTROL);
robot.keyRelease(KeyEvent.VK_P );

Thread.sleep(500);

//Alt+U
robot.keyPress(KeyEvent.VK_ALT );
robot.keyPress(KeyEvent.VK_U );
robot.keyRelease(KeyEvent.VK_ALT );
robot.keyRelease(KeyEvent.VK_U );

Thread.sleep(500);

//Enter
robot.keyPress(KeyEvent.VK_ENTER);
robot.keyRelease(KeyEvent.VK_ENTER );

Thread.sleep(500);

//Alt+D+N
robot.keyPress(KeyEvent.VK_ALT );
robot.keyPress(KeyEvent.VK_D );
robot.keyPress(KeyEvent.VK_U );
robot.keyRelease(KeyEvent.VK_ALT );
robot.keyRelease(KeyEvent.VK_D );
robot.keyRelease(KeyEvent.VK_U );

Thread.sleep(500);
}
catch(Exception e){ }

//@@end
}

Hola, pues si atrapas la exception, ahora bien si quieres visualizar el tipo de exception ocurrida debes agregar el el boque catch la linea de impresion de la traza de la exception sucitada

saludos