BluetoothAdapter issue?

I am just writing the following code and getting some issue on "mBtAdapter.startDiscovery();", I can't understand what the hell is going on, I just want to start bluetooth and add devices to my array as my app is loaded.

package com.wiztech.veer;

import android.app.Activity;
import android.bluetooth.BluetoothAdapter;
import android.os.Bundle;
import android.widget.ArrayAdapter;

public class BLU_TESTActivity extends Activity {

// Member fields
private BluetoothAdapter mBtAdapter;
private ArrayAdapter<String> mPairedDevicesArrayAdapter;
private ArrayAdapter<String> mNewDevicesArrayAdapter;

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    // Get the local Bluetooth adapter
    mBtAdapter = BluetoothAdapter.getDefaultAdapter();
    mBtAdapter.startDiscovery();

}
}

The errors are

07-26 13:21:52.178: ERROR/AndroidRuntime(4962): ERROR: thread attach failed
07-26 13:21:53.518: ERROR/ActivityManager(117): fail to set top app changed!
07-26 13:21:53.668: ERROR/AndroidRuntime(4970): ERROR: thread attach failed开发者_JS百科

Please Help !

Have u tried broadcastReceiver(), or u may missing permissions in manifest.xml.