В чём моя ошибка?

import sys

from DELETE_WND import *
from Add_Wnd import *
from HFD import *
from PyQt5 import QtCore, QtGui, QtWidgets


class DELETEWINDOW(QtWidgets.QMainWindow):
    def __init__(self, parent=None):
        QtWidgets.QWidget.__init__(self, parent)
        self.ui = Ui_DEL_WND()
        self.ui.setupUi(self)

class ADDWINDOW(QtWidgets.QMainWindow):
    def __init__(self, parent=None):
        QtWidgets.QWidget.__init__(self, parent)
        self.ui = Ui_ADD_WINDOW()
        self.ui.setupUi(self)
        self.ui.lineEdit.setMaxLength(10)
        self.ui.lineEdit_2.setMaxLength(10)
        self.ui.lineEdit_3.setMaxLength(10)
        self.ui.pushButton.clicked.connect(self.button)

    def button(self):
        text1 = self.ui.lineEdit.text()
        text2 = self.ui.lineEdit_2.text()
        text3 = self.ui.lineEdit_3.text()
        

class MyWin(QtWidgets.QMainWindow):
    def __init__(self, parent=None):
        QtWidgets.QWidget.__init__(self, parent)
        self.ui = Ui_MainWindow()
        self.ui.setupUi(self)
        self.ui.ADD_BTN.clicked.connect(self.ADD)
        self.ui.DELETE_BTN.clicked.connect(self.DELETE)

        self.ui.textBrowser.setText(text1)
        self.ui.textBrowser_2.setText(text2)
        self.ui.textBrowser_3.setText(text3)

    def ADD(self):
        dialog = ADDWINDOW(self)
        dialog.show()

    def DELETE(self):
        dialog = DELETEWINDOW(self)
        dialog.show()
        


if __name__ == "__main__":
    app = QtWidgets.QApplication(sys.argv)
    myapp = MyWin()
    myapp.show()
    sys.exit(app.exec_())