Cannot open file SQLite error in Android App

I'm new to SQLite and this is the first database that I'm using in an App, so I'm having some troubles.

At first, I could use the database with no problems, I was fetching the data correctly and it was working fine. But I realized that, after reinstalling the App, it was throwing me a SQLite cannot open file error.

Now it's pretty much crashed and I don't know why. It never works, it always throws me the Cannot open file error.

I never write data to my database, I only use it to fetch some data. This is the content of my DatabaseHelper class:

public static String DB_PATH = "/data/data/myapp.app.databasetest/databases/";

public static String DB_NAME = "mydatabase.db"; public static final int DB_VERSION = 2;

private SQLiteDatabase myDB;
private Context context;

public DatabaseHelper(Context context) {
  super(context, DB_NAME, null, DB_VERSION);
  this.context = contex
}

//check if database exists
private boolean checkDataBase() {
  SQLiteDatabase tempDB = null;

  try {
    String myPath = DB_PATH + DB_NAME;
    //the error appears in the next line
    tempDB = SQLiteDatabase.openDatabase(myPath, null,  SQLiteDatabase.OPEN_READWRITE); //<--Here appears the ERROR
  } catch (SQLiteException e) {
    Log.e("tle99 - check", e.getMessage());
  }
  if (tempDB != null)
      tempDB.close();
  return tempDB != null ? true : false;
}

//copy database to assets folder
public void copyDataBase() throws IOException { 
  try {
    InputStream myInput = context.getAssets().open(DB_NAME);
    String outputFileName = DB_PATH + DB_NAME;
    OutputStream myOutput = new FileOutputStream(outputFileName);

    byte[] buffer = new byte[1024];
    int length;

    while((length = myInput.read(buffer))>0){
      myOutput.write(buffer, 0, length);
    }

    myOutput.flush();
    myOutput.close();
    myInput.close();
  } catch (Exception e) {
   Log.e("tle99 - copyDatabase", e.getMessage());
  }

}

public void openDataBase() throws SQLException {
  String myPath = DB_PATH + DB_NAME;
  myDB = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READWRITE);
}

public void createDataBase() throws IOException {

  boolean dbExist = checkDataBase();

  if (dbExist) {

  } else {
    this.getReadableDatabase();
    try {
      copyDataBase();
    } catch (IOException e) {
      Log.e("tle99 - create", e.getMessage());
    }
  }
}

The error appears when calling the checkDataBase() function (there's a comment next to the line) and as I said it's a SQLite cannot open file. This is the part in the Logcat where I see the error:

03-31 19:09:18.464 21825-21825/? E/SQLiteLog: (14) cannot open file at line 30052 of [b3bb660af9]
03-31 19:09:18.464 21825-21825/? E/SQLiteLog: (14) os_unix.c:30052: (2) open(/data/data/myapp.app.databasetest/databases/mydatabase.db) - 
03-31 19:09:18.466 21825-21825/? E/SQLiteDatabase: Failed to open database '/data/data/myapp.app.databasetest/databases/mydatabase.db'.

I sincerely don't know how to fix it. I've been stuck on it for a couple days now and it's being a real pain to fix. It was working fine until I would reinstall the App, but now it's never working. I don't know what's wrong with my code.

Any help would be much appreciated! Thanks in advance.