谁能告诉我我的凯撒算法出了什么问题？

def caesar_encrypt(text, shift):
    result = ""
    for char in text:
        if char.isalpha():
            shift_amount = shift % 26
            if char.islower():
                new_char = chr((ord(char) - ord('a') + shift_amount) % 26 + ord('a'))
            else:
                new_char = chr((ord(char) - ord('A') + shift_amount) % 26 + ord('A'))
            result += new_char
        else:
            result += char
    return result

shift_amount = (shift % 26 + 26) % 26

print(f"Original text: {text}")
print(f"Shift amount: {shift}")
print(f"Encrypted text: {result}")

assert caesar_encrypt("hello", 1) == "ifmmp"
assert caesar_encrypt("world", -1) == "vnqkc"
assert caesar_encrypt("Hello, World!", 3) == "Khoor, Zruog!"