python script to accept 8 char password with these conditions only: 2 num, 2 upper, 2 lower, and 2 special

This is what I've done till now. And when it goes wrong it doesn't print 'Not Okay'. I'm still not able to figure out how to check special chars.

#!/usr/bin/python

def passw_check():
    passin = raw_input("Enter the password")

    if len(passin) == 8:       # checking total length of password
        if sum(map(str.isupper, passin))== 2: #check 2 upper chars
            if sum(map(str.islower, passin))== 2:  #check 2 lower chars
                if sum(map(str.isdigit, passin))== 4:  #check 2 digits chars
                    print 'Passwords Okay'
                else: 
                    print 'Not Okay!'

passw_check()