c# If else if statement event triggers before else if does

so I have hidden buttons, that I only want to show when maxAttempts has been reached, with the code below, the buttons open after the first wrong attempt. Also while I'm at it, I want to disable a button and a textbox at game over, but when I write btncheckAnswer.disable and txtResult.disable I see exceptions.

Any suggestions?

 private void btnCheckAnswer_Click(object sender, EventArgs e)
    {

        var userAnswer = double.Parse(txtResult.Text);
        if (!puzzle.CheckTheAnswer(userAnswer))
        {
            MessageBox.Show("Wrong");
            numAttempts++;
            if (numAttempts < maxAttempts)
            {  // UpdateImage();
                NextQuestion();
            }
            else
                if (numAttempts == maxAttempts)
                {
                    MessageBox.Show("Game Over");
                    btnClose.Show();
                    btnNewGame.Show();
                    //btnCheckAnswer.disable();
                    //txtResult.disable;()
                    //Stop the game ();
                    //Block text box from receiving data

                    return;
                }

        }

        else MessageBox.Show("Smarty Pants, You're Right!!");
        {
            NextQuestion();
        }
        return;