It keeps saying my camera can't access external storage OR it says the camera is working. HELP!!!!!!!!!

public static final String TAG = MainActivity.class.getSimpleName();
public static final int TAKE_PHOTO_REQUEST = 0;
public static final int TAKE_VIDEO_REQUEST = 1;
public static final int PICK_PHOTO_REQUEST = 2;
public static final int PICK_VIDEO_REQUEST = 3;


public static final int MEDIA_TYPE_IMAGE = 4;
public static final int MEDIA_TYPE_VIDEO = 5;

protected Uri mMediaUri;

protected DialogInterface.OnClickListener mDialogListner = new DialogInterface.OnClickListener() {

    @Override
    public void onClick(DialogInterface dialog, int which) {
        switch(which){
        case 0: //Take a picture
            Intent takePhotoIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
            mMediaUri = getOutputMediaFileUri(MEDIA_TYPE_IMAGE);

            if(mMediaUri == null){
                //display and error
                Toast.makeText(MainActivity.this, R.string.error_external_storage, Toast.LENGTH_LONG).show();
            }
            else{
                takePhotoIntent.putExtra(MediaStore.EXTRA_OUTPUT, mMediaUri);
                startActivityForResult(takePhotoIntent, TAKE_PHOTO_REQUEST);
            }
            break;
        case 1: //Take video
            break;
        case 2: // Choose a Picture
            break;
        case 3: // Choose Video
            break;
        }

    }

    private Uri getOutputMediaFileUri(int mediaType) {
         // To be safe, you should check that the SDCard is mounted
        // using Environment.getExternalStorageState() before doing this.
        if(isExternalStorageAvailable()){
            //get the URI

            //1. Get the external storage
            String appName = MainActivity.this.getString(R.string.app_name);
            File mediaStorageDir = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES), 
                    appName);
            //2. Create our subdirectory
            if(! mediaStorageDir.exists()){
                if(! mediaStorageDir.mkdirs());
                    Log.e(TAG, "Failed to create directory.");
                    return null;
            }
            //3. Create a file name

            //4. Create the file
            File mediaFile;
            Date now = new Date();
            String timestamp = new SimpleDateFormat("yyyyMMdd_HHmmss", Locale.US).format(now);

            String path = mediaStorageDir.getPath() + File.separator;
            if(mediaType == MEDIA_TYPE_IMAGE){
                mediaFile = new File(path + "IMG_" + timestamp + ".jpg");
            }

            else if(mediaType == MEDIA_TYPE_VIDEO){
                mediaFile = new File(path + "VID_" + timestamp + ".mp4");
            }
            else{
                return null;
            }
            Log.d(TAG,"File: " + Uri.fromFile(mediaFile));
            //5. Return the file's URI
            return Uri.fromFile(mediaFile);
        }
        else{
            return null;
        }


    }
    private boolean isExternalStorageAvailable(){
        String state = Environment.getExternalStorageState();

        if(state.equals(Environment.MEDIA_MOUNTED)){
            return true;
        }
        else{
            return false;
        }
    }
};

/**
 * The {@link android.support.v4.view.PagerAdapter} that will provide
 * fragments for each of the sections. We use a {@link FragmentPagerAdapter}
 * derivative, which will keep every loaded fragment in memory. If this
 * becomes too memory intensive, it may be best to switch to a
 * {@link android.support.v13.app.FragmentStatePagerAdapter}.
 */
SectionsPagerAdapter mSectionsPagerAdapter;

/**
 * The {@link ViewPager} that will host the section contents.
 */
ViewPager mViewPager;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    requestWindowFeature(Window.FEATURE_INDETERMINATE_PROGRESS);
    setContentView(R.layout.activity_main);

    ParseAnalytics.trackAppOpened(getIntent());

    ParseUser currentUser = ParseUser.getCurrentUser();
    if(currentUser == null){
    navigateToLogin();
    }
    else{
        Log.i(TAG, currentUser.getUsername());
    }


    // Set up the action bar.
    final ActionBar actionBar = getActionBar();
    actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);

    // Create the adapter that will return a fragment for each of the three
    // primary sections of the activity.
    mSectionsPagerAdapter = new SectionsPagerAdapter(this,getSupportFragmentManager());

    // Set up the ViewPager with the sections adapter.
    mViewPager = (ViewPager) findViewById(R.id.pager);
    mViewPager.setAdapter(mSectionsPagerAdapter);

    // When swiping between different sections, select the corresponding
    // tab. We can also use ActionBar.Tab#select() to do this if we have
    // a reference to the Tab.
    mViewPager
            .setOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() {
                @Override
                public void onPageSelected(int position) {
                    actionBar.setSelectedNavigationItem(position);
                }
            });

    // For each of the sections in the app, add a tab to the action bar.
    for (int i = 0; i < mSectionsPagerAdapter.getCount(); i++) {
        // Create a tab with text corresponding to the page title defined by
        // the adapter. Also specify this Activity object, which implements
        // the TabListener interface, as the callback (listener) for when
        // this tab is selected.
        actionBar.addTab(actionBar.newTab()
                .setText(mSectionsPagerAdapter.getPageTitle(i))
                .setTabListener(this));
    }
}

private void navigateToLogin() {
    //if there is no current user, execute these lines. (Which takes them to the login screen)
    Intent intent = new Intent(this, LoginActivity.class);
    intent.addFlags(intent.FLAG_ACTIVITY_NEW_TASK);
    intent.addFlags(intent.FLAG_ACTIVITY_CLEAR_TASK);
    startActivity(intent);
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}


@Override
public boolean onOptionsItemSelected(MenuItem item) {
        int itemId = item.getItemId();



        switch(itemId){
        case R.id.action_logout:
            ParseUser.logOut();
            navigateToLogin();
        case R.id.action_edit_friends:
            Intent intent = new Intent(this, EditFriendsActivity.class);
            startActivity(intent);
        case R.id.action_camera:
            AlertDialog.Builder builder = new AlertDialog.Builder(this);
            builder.setItems(R.array.camera_choices, mDialogListner );
            AlertDialog dialog = builder.create();
            dialog.show();
        }
        if (itemId == R.id.action_logout) {
            ParseUser.logOut();
            navigateToLogin();
            return true;
        }
        else if(itemId ==R.id.action_edit_friends ){
            Intent intent = new Intent(this, EditFriendsActivity.class);
            startActivity(intent);
        }

        return super.onOptionsItemSelected(item);
}

@Override
public void onTabSelected(ActionBar.Tab tab,
        FragmentTransaction fragmentTransaction) {
    // When the given tab is selected, switch to the corresponding page in
    // the ViewPager.
    mViewPager.setCurrentItem(tab.getPosition());
}

@Override
public void onTabUnselected(ActionBar.Tab tab,
        FragmentTransaction fragmentTransaction) {
}

@Override
public void onTabReselected(ActionBar.Tab tab,
        FragmentTransaction fragmentTransaction) {
}