Send random text everytime on chat screen

class chatting:
    def chat1(self,chatmsg1):
        if exists("person1.png"):
            type(chatmsg1)
        else:
            click("person1.png")
            while not exists("person1.png",0):
                wait(1)
            wait(2)
            type(Key.TAB * 2)
            type(chatmsg1 + Key.ENTER)
            wait(2)

    def chat2(self,chatmsg2):
        if exists("person2.png"):
            type(chatmsg2)
        else:
            click("person2.png")
            while not exists("person2.png",0):
                wait(1)
            type(Key.TAB * 5)
            type(chatmsg2 + Key.ENTER)
            wait(2)

#comres (Common resource)
chatmsg1 = ''.join(random.sample(string.letters, num1))
chatmsg2 = ''.join(random.sample(string.letters, num2))

#Calling
chatting.chat1(comres.chatmsg1)
chatting.chat2(comres.chatmsg2)

Every time it is sending the same text. Is anything wrong in this code.Please help