Using modify to change the password failed

[linzehai0801]

I use
new_password_entry = {'unicodePwd': [(MODIFY_REPLACE, [new_password.encode('utf-16-le')])]}
conn.modify(entry.entry_dn, new_password_entry)
When changing the password, the password was successfully changed but authentication failed.
Using
password_modify = conn. The extend. Microsoft. Modify_password (entry. Entry_dn new_password)
change the password, authentication is successful. Why, please?