Microsoft OLE DB Provider For ODBC Drivers Error '

Hi guys

I wanna display the compname [in competencies tbl], firstname & surname [in users tbl], position level [in positions tbl] and userlevel [in compuser tbl] but i get the ff error msg

Microsoft OLE DB Provider for ODBC Drivers error '80040e14'
[Microsoft][ODBC SQL Server Driver][SQL Server]The column prefix 'CompUser' does not match with a table name or alias name used in the query.

My code:

SELECT compname, firstname,surname ,level AS positionlevel
FROM positions, compuser, users A, comppos
INNER JOIN Competencies
ON comppos.Compid = competencies.Compid
RIGHT JOIN Users
ON CompUser.UserID = Users.UserID
WHERE Users.UserID = '999209'
OR Users.UserID = 'helpdesk1'
OR Users.UserID = '999339'
OR Users.UserID = 'helpdesk5'
ORDER BY CompName

Pls kindly help
Noks