Update database on android sqlite problems

I'm trying to update a row in my database but my code is not working, it changes nothing. Is there something missing in the code?

    public boolean updateContact(Contact contact) {
        db = getWritableDatabase();

    ContentValues values = new ContentValues();

    values.put(KEY_NAME, contact.getName());
    values.put(KEY_PHONE, contact.getPhone());
    values.put(KEY_EMAIL, contact.getEmail());
    values.put(KEY_ADDRESS, contact.getAddress());
    values.put(KEY_IMAGEURI, contact.getImageUri().toString());

    return (db.update(TABLE_CONTACTS, values, KEY_ID + "=?", new String[] { "" + contact.getId() }) > 0);
    }