Hi Maryann,
Please find below some few amendments to the earlier posting.
Note that if you are extending the probation of an employee it means that there is a problem you want to deal with. It is therefore fair that you give reason for the extension so that the probationer will improve upon his or her performance.
This letter should not be in a memo form but in the format like the appointment letter.
"Yours sincerely" was used because he is currently a staff and not in the strictest sense an outsider. not also that these are the new trends in letter with sautations Dear Mr./Mrs./Dr. Rev. etc
You should also always ptu your name and designation.
Please you may letter me know your reactions.
Paa kow