This code will help you...

import javax.microedition.midlet.*;
import com.nokia.mid.ui.DeviceControl;
import javax.microedition.lcdui.*;


public class vibramidlet extends MIDlet implements CommandListener{

private Command _cmdExit = null;
private Command _cmdVibrate = null;
private Command _cmdBacklightOn = null;
private Command _cmdBacklightOff = null;
private Command _cmdBacklightFlash = null;


private Form _mainForm = null;
private Display _display = null;

public vibramidlet() {

_cmdExit = new Command("Exit", Command.EXIT, 1);
_cmdVibrate = new Command("Vibration", Command.SCREEN, 1);
_cmdBacklightOn = new Command("Backlight ON", Command.SCREEN, 2);
_cmdBacklightOff = new Command("Backlight OFF", Command.SCREEN, 2);
_cmdBacklightFlash = new Command("Flash Backlight", Command.SCREEN, 3);

_mainForm = new Form("Startvibra");
_display = Display.getDisplay(this);

_mainForm.addCommand(_cmdExit);
_mainForm.addCommand(_cmdVibrate);
_mainForm.addCommand(_cmdBacklightOn);
_mainForm.addCommand(_cmdBacklightOff);
_mainForm.addCommand(_cmdBacklightFlash);

_mainForm.setCommandListener(this);
}

protected void startApp() throws MIDletStateChangeException {
_display.setCurrent(_mainForm);
}

protected void pauseApp() { }

protected void destroyApp(boolean uc) { }

public void commandAction(Command cmd, Displayable disp) {

if(cmd == _cmdExit){
_mainForm.append("EXIT MIDlet... \n");
this.destroyApp(false);
notifyDestroyed();

}
else if(cmd == _cmdVibrate){
_mainForm.append("Vibra for 2 Seconds (Freq:100)... \n");
DeviceControl.startVibra(100, 2000);

}
else if(cmd == _cmdBacklightOn){
_mainForm.append("Turn Backlight ON \n");
DeviceControl.setLights(0, 100);

}
else if(cmd == _cmdBacklightOff){
_mainForm.append("Turn Backlight OFF \n");
DeviceControl.setLights(0, 0);

}

}
}

I tried the above sample code on both NOKIA 3650(not worked) and NOKIA 7210(worked)..can some one tell what may be the reason for the above sample code working in nokia 7210 but not in the 3650...i have tried in n70
also but failed....

__________________
cheers
Aman