Passed all Tests but doesn't work correctly

Hi there, I got alle tasks for the minesweeper game passed but the game doesn't work as intended. The recursion of openTile(x,y) must be incorrect because it opens too many tiles and some tiles stay orange and can't be clicked anymore. Can anybody help me finding my mistake. Thank You Markus

private void openTile(int x, int y) {
        if (isGameStopped || gameField[y][x].isOpen || gameField[y][x].isFlag) {}
        else {
            gameField[y][x].isOpen = true;
            if (!gameField[y][x].isMine) {
                setScore(score += 5);
            }
            countClosedTiles--;


            if (gameField[y][x].isMine) {
                setCellValue(x, y, MINE);
                setCellValueEx(x, y, Color.RED, MINE);
                gameOver();
            } else {
                if (countClosedTiles == countMinesOnField) {
                    win();
                }
                if (gameField[y][x].countMineNeighbors == 0) {
                    setCellValue(x, y, "");
                    setCellColor(y, x, Color.GREEN);
                    for (GameObject feld : getNeighbors(gameField[y][x])) {
                        if (!feld.isOpen) openTile(feld.x, feld.y);
                    }
                } else {
                    setCellValueEx(x, y, Color.GREEN, String.valueOf(gameField[y][x].countMineNeighbors));

                }
            }
            }


            }