MySQL FULL JOIN not working but RIGHT and LEFT join works

Question

This is driving me nuts. I have two tables that I am attempting to preform a join on, usersXstats and usersXstats_alltime.

Both tables have the same columns: id, us

Answer 1

SELECT Person1.Firstname, Person2.State
FROM Person1
left JOIN Person2
ON Person1.PersonID=Person2.PersonID
UNION
SELECT Person1.Firstname, Person2.State
FROM Person1
right JOIN Person2
ON Person1.PersonID=Person2.PersonID;

is working superbly.