Consulta Com Apelidos

SELECT Evento.CharID as IDChar
FROM _LogEventChar as Evento

WHERE Evento.EventID = 4
AND NOT EXISTS (SELECT *
 FROM _LogEventChar as Evento1
 WHERE Evento1.EventID = 6
 AND Evento1.CharID = Evento.IDChar)

ORDER BY EventTime DESC

erro :

Msg 207, Level 16, State 1, Line 1
Invalid column name 'IDChar'.

pessoal alguém sabe o porque do erro?