获取设备IMEI信息报空指针

Question

public class MyApplication extends Application {

public static final String TAG = "MyApplication";

private static MyApplication instance=null;

public MyApplication() {

}

@Override
public void onCreate() {
    // TODO Auto-generated method stub
    super.onCreate();
    instance=this;
}

/**
 * 获取一个实例
 */
public static MyApplication getinstance() {
    if(instance==null){
        instance=new MyApplication();
    }
    return instance;
}
}

*****************************************************************
public class Utils {

/**
 * 获取手机串号
 */
public static String getPhoneSN() {
    TelephonyManager telmanage =  (TelephonyManager) MyApplication.getinstance()
            .getSystemService(Context.TELEPHONY_SERVICE);
    String deviceId = telmanage.getDeviceId();
    Log.e("Utils", deviceId);
    return deviceId;
}


为什么获取不到  IMEI  啊？