Why isn't my else block being executed? [duplicate]

This question already has an answer here:

• How do I test one variable against multiple values? 16 answers

def check_letter(self):

    if self.entered_letter.text().upper() or self.entered_letter.text().lower() in self.word:
        self.guessed_letters += self.entered_letter.text().upper()
        self.guessed_letters += self.entered_letter.text().lower()
        self.correct.setVisible(True)
        QApplication.processEvents()
        sleep(0.2)
        self.correct.setVisible(False)
        QApplication.processEvents()

    else:
        self.number += 1
        self.image.setPixmap(QPixmap('hangman_{}.png'.format(self.number)).scaled(100, 200, Qt.KeepAspectRatio, Qt.FastTransformation))
        self.incorrect.setVisible(True)
        QApplication.processEvents()
        sleep(0.2)
        self.incorrect.setVisible(False)
        QApplication.processEvents()

    blank_word = ''
    for i in self.word:
        if i in self.guessed_letters:
            blank_word += i

        else:
            blank_word += '_ '

    blank_word.rstrip()

    self.blank_word_label.setText(blank_word)
    self.entered_letter.setText('')

This is the hangman game project I'm working on using PyQt5 with Python 3.5 on my Windows 7 32-bit machine. The problem is that my else-block does not execute in this function no matter what I do, but the if-block seems to always execute no matter what or at least the last 5 lines in the if-block do.

Full Code: http://ift.tt/2fs3Ini