how can i use union and order by in mysql ?

select * from _member_facebook 
inner join _member_pts 
ON _member_facebook._fb_owner=_member_pts._username 
where _member_facebook._promote_point = 9 
ORDER BY RAND() limit 2 
UNION ALL
select * from _member_facebook 
inner join _member_pts 
ON _member_facebook._fb_owner=_member_pts._username 
where _member_facebook._promote_point = 8 limit 3

give me error 

#1221 - Incorrect usage of UNION and ORDER BY

any one can help ?

mysql sql-order-by union
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