Why do exists & In fail?

[john sayre]

I'm trying to do some simple in or exists queries, but am getting syntax error on 
queries that appear to be correct.  If I run the outside & sub queries alone, not 
problem.  In the In subquery, if I hardcode a value, ok but this fails:
 
SELECT * FROM erestbase WHERE erestbase.id in(SELECT distinct idcid.id FROM idcid)
 
This is stupid. Nothig would be wrong here in sqlServer etc.  Both ids are integer 
values.