JOptionPane.showMessageDialog- Question-Easy Code

I have this code and always that I execute appears two messages. JOptionPane.showMessageDialog(null, "ERROR DE PENSION"); JOptionPane.showMessageDialog(null, "ERROR PROMEDIO");

I don't understand why. Because I put this messages only if I choose certain values. But even if I choose other values still keep going these 2 messages.

Please, help me understand why!!

    int pension;
    String categoria;
    Double promedio;
    Double descuento;

    categoria = txtTP.getText().toString();
    System.out.println("hola" +categoria);
    if (categoria.equalsIgnoreCase("A"))
        pension = 550;

    else
        if(categoria.equalsIgnoreCase("B"))
            pension = 500;

        else
            if(categoria.equalsIgnoreCase("C"))
                pension = 460;
            else
                if (categoria.equalsIgnoreCase("D"))
                pension = 400;
                else
                pension = 0;
                JOptionPane.showMessageDialog(null, "ERROR DE PENSION");

                System.out.println(pension);


    promedio = Double.parseDouble(txtP.getText());
    if (promedio>0 && promedio<14)
        descuento=0.00;
    else if (promedio >=14 && promedio < 16)
        descuento = 0.1;
    else if (promedio >=16 && promedio <18 )
        descuento = 0.12;
    else if (promedio >=18 && promedio <=20)
        descuento = 0.15;
    else
        descuento = 0.00;
        JOptionPane.showMessageDialog(null, "ERROR PROMEDIO");



textM.setText("Tienes" +descuento +"% de rebaja");