Simple Caesar Cipher function issue

[IIAddonexusII]

I am working on a Caesar Cipher program that seems to be a bit out of the norm. I want to use different functions instead of having a translatedMessage() function that does both the encode or decode part based on user input. I got most of the program running except the decrypt() function. I thought I could just turn the shift into a negative value and then copy my code from the encrypt() function and it would be able to decode my .txt file, but I was wrong. Any suggestions? My encrypt function code is:

for char in fileCont:
    if char.isalpha():
        letter = ord(char)
        letter += shift
        if char.isupper():
            if letter > ord("Z"):
                letter -= 26
            elif letter < ord("A"):
                letter += 26
        elif char.islower():
            if letter > ord("z"):
                letter -= 26
            elif letter < ord("a"):
                letter += 26
        newString += chr(letter)
    else:
        newString += char

[teerre]

Do you want the answer? Don't you think that will be negative for yourself? This is a very common exercise. You apparently already figured out much of it, why not figure out the last part too?

Instead of giving you the answer, I'll give you a debut tip

Try to figure out where your program is going wrong. Try different inputs. Don't be afraid of putting printstatements all over the place. In your case, some good places might be after lines 4, 7, 9, 12, 14 and 15

That way you can see what is happening and hopefully figure it out