i have written a small code to display latitude and longitude.
it is working correctly in emulator.but not at all working on actual device.
what could be the issue
plz hlp me

Why don't you post the code you are having trouble with?

A little hard to help when we can't see the code

package org.GPS;

import android.app.Activity;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.widget.Toast;

public class GPS extends Activity implements LocationListener
{

@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
Intent i = new Intent();
ComponentName comp = new ComponentName("com.android.settings",
"com.android.settings.SecuritySettings");
i.setComponent(comp);
startActivity(i);
LocationManager lm = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
lm.requestLocationUpdates(LocationManager.GPS_PROVIDER,1, 1,this);
Location currentLocation = lm.getLastKnownLocation(LocationManager.GPS_PROVIDER);
if(currentLocation != null)
{
double Latitude = currentLocation.getLatitude();
double Longitude = currentLocation.getLongitude();
Toast.makeText(GPS.this,"Latitude="+Latitude+"\nLongitude"+Longitude,Toast.LENGTH_LONG).show();
}
else
{
Toast.makeText(GPS.this,"No GPS 1",Toast.LENGTH_LONG).show();
}

}

@Override
public void onLocationChanged(Location location)
{
if (location != null)
{
double longitude = location.getLongitude();
double latitude = location.getLatitude();
Toast.makeText(GPS.this,"Longiude="+longitude+"\nLatitude="+latitude,Toast.LENGTH_LONG).show();

}
else
{
Toast.makeText(GPS.this,"No GPS 2",Toast.LENGTH_LONG).show();
}

}

@Override
public void onProviderDisabled(String provider)
{
// TODO Auto-generated method stub

}

@Override
public void onProviderEnabled(String provider)
{
// TODO Auto-generated method stub

}

@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
// TODO Auto-generated method stub

}
}