Why doesn't the given image appear on the PyQt5 button?

Question

Python

UPD: Reinstalled PyQt and everything works now
I'm learning how to make applications in Python 3 using the PyQt5 module. I have a list that stores the paths to images that I want to put on buttons. When I try to attach these images to buttons, the buttons remain empty. Please tell me what am I doing wrong?

from PyQt5 import QtCore, QtWidgets, QtGui

list1 = ['picture1.png', 'picture2.png']

class MyWindow(QtWidgets.QWidget):
    def __init__(self, parent=None):
        QtWidgets.QWidget.__init__(self, parent)
        self.button = QtWidgets.QPushButton("Button")
        self.box1 = QtWidgets.QVBoxLayout()
        self.box1.addWidget(self.button)
        self.setLayout(self.box1)
        self.pictures()

    def pictures(self):
        self.box2 = QtWidgets.QHBoxLayout()
        for picture in list1:
            self.button_picture = QtWidgets.QPushButton(self)
            self.button_picture.setIcon(QtGui.QIcon(picture))
            self.button_picture.setIconSize(QtCore.QSize(100, 100))
            self.box2.addWidget(self.button_picture)
        self.box1.addLayout(self.box2)

if __name__ == "__main__":
    import sys
    app = QtWidgets.QApplication(sys.argv)
    window = MyWindow()
    window.show()
    sys.exit(app.exec_())