can't use 'minus', can't use 'not in' what can i use?!?

[Matt Williams]

select users.uid, users.name from users
where users.name not in (SELECT users.name FROM installmatrix
inner join users on installmatrix.uid = users.uid
WHERE spid = 1)

1st query works independently
2nd query works independently

put the 2nd into a subquery and use 'NOT IN' and it bombs out.... what gives??
'Not in' was my solution to a lack of MINUS operator in SQL