In the main activity I create database

class DBHelper extends SQLiteOpenHelper {

        public DBHelper(Context context) {

               super(context, "myDB", null, 1);
        }

        @Override
        public void onCreate(SQLiteDatabase db) {
          db.execSQL("create table mytable ("
                  + "id integer primary key autoincrement," 
                  + "name text," 
                  + "obId text," 
                  + "latit text,"
                  + "long text" + ");");
        }

        @Override
        public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

        }
      }

In the second activity I call the class of database

MainActivity myActivity = new MainActivity();
dbHelper = myActivity.new DBHelper(myActivity);

And insert data

ContentValues cv = new ContentValues();
db = openOrCreateDatabase("myDB.db", SQLiteDatabase.OPEN_READWRITE, null);
cv.put("name", textViewName.getText().toString());
long rowID = db.insert("mytable", null, cv);
db.insert("mytable", null, cv);
dbHelper.close();

The output "rowID" is "-1". I do not understand why this is happening