[Android] ไม่สามารถ read.text จาก SD Card ได้ครับผมช่วยทีครับ

package com.example.apptest1;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;

import android.os.Environment;
import android.app.Activity;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

@SuppressWarnings("unused")
public class MainActivity extends Activity {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
             
        final File sdcard = Environment.getExternalStorageDirectory(); // /mnt/sdcard/
        
        // button1
        final Button btn1 = (Button) findViewById(R.id.button1);
        // textView1
        final TextView txtV = (TextView) findViewById(R.id.textView1);
        
        // Perform action on click 
        btn1.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
            	
            		/*** Read Text File in SD Card ***/
					try {
						
					String path = sdcard + "/data/myFolder/HS1C.text";
					
					File file = new File(path);
					
					BufferedReader br = new BufferedReader(new FileReader(file));
					String line;
					line = br.readLine();
					br.close();
					file = null;
					
					txtV.setText(line);
			 		   
				} catch (Exception e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
			 		   Toast.makeText(MainActivity.this, "Failed! = " + e.getMessage() ,
					 		     Toast.LENGTH_LONG).show();   
				}
           

            }
        });
               
    }
    
    
    }
	

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.example.apptest1.MainActivity" >

    
<Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="18dp"
        android:text="Read Text File" />

    <TextView
        android:id="@+id/textView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/button1"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="23dp"
        android:text="TextView" />
    
</RelativeLayout>