PyQt5 button click not work in imported class

In file index.py this line works fine, but in imported class similar line won't work! I can't understand why. Here is code:

index.py

import sys
from PyQt5 import uic
from PyQt5.QtWidgets import QMainWindow, QApplication

class MainWindow(QMainWindow):
def __init__(self):
super().__init__()

# Set up the MainWindow from Designer.
uic.loadUi("mw.ui", self)

# Connect up the buttons.
self.pushButton.clicked.connect(self.BtnClck)

self.show()

def BtnClck(self):
# Set up the ContentWindow from Designer.
from form1 import form1
form1(self.mn_general)
self.mn_general.pushButton_2.clicked.connect(form1 .BtnClck1) #this works fine

if __name__ == '__main__':
app = QApplication(sys.argv)
ex = MainWindow()
sys.exit(app.exec_())

form1.py

from PyQt5 import uic

class form1:
def __init__(self, obj):
super().__init__()
uic.loadUi("form1.ui", obj)

obj.pushButton.setText('TextChanged on init') #this works fine
obj.pushButton.clicked.connect(self.BtnClck1) #this NOT works
obj.pushButton.click() #this make previous line works fine!

def BtnClck1(self):
print('SecondWindowPrint')

What doesn't work about it?
Invalid syntax, error message printed at run time, no message when clicked...?

Please use [code]...[/code] tags around code.

Then i click pushButton by mice, it not work, no BtnClck1 method is called and no print-SecondWindowPrint.

But if i call PushButton click programmatically, it works fine.

And PushButton works fine if i make connect from index.py

Here is full code on GitHub github.com/m0x3/test1

Right answer is put instance of form1 class in a public variable in MainWindow class.
Need change BtnClck function in Index.py like this:

Code:

---

def BtnClck(self):
    # Set up the ContentWindow from Designer.
    from form1 import form1
    self.Form=form1(self.mn_general)
    self.mn_general.pushButton_2.clicked.connect(form1.BtnClck1) #this works fine

---

Really thanks to Saj Haz from StackOverflow