Too many fields defined in query

[Lisa b]

I have created a query [CC final form] that should put
together/build fields [SocEm], [CogDev] and [PysDev] from
4 different queries. When I attemp to run the query, I get
the error "3190 -too many fields defined". I only have 8
fields defined... The query works if I leave out any one
of the 3 nested IIF statements... but I need all three so
I can group all results by [CC Coded].CNTRNAME and [CC
Coded].ROOM.

Any ideas or suggestions?
Thanks!
Lisa b

Here's the code:
SELECT [CC Coded].IDNO, [CC Coded].CNTRNAME, [CC
Coded].ROOM, [CC Coded].[age on Sept 1], [CC
Coded].Teacher, IIf([SEper] Is Not Null,[SEper],IIf
([SEper2] Is Not Null,[SEper2],IIf([SEper3] Is Not Null,
[SEper3],[SEper4]))) AS SocEm, IIf([CDper] Is Not Null,
[CDper],IIf([CDper2] Is Not Null,[CDper2],IIf([CDper3] Is
Not Null,[CDper3],[CDper4]))) AS CogDev, IIf([PDper] Is
Not Null,[PDper],IIf([PDper2] Is Not Null,[PDper2],IIf
([PDper3] Is Not Null,[PDper3],[PDper4]))) AS PysDev
FROM ((([CC Coded] LEFT JOIN [CC percents 3-6 and younger]
ON [CC Coded].AssNO = [CC percents 3-6 and younger].AssNO)
LEFT JOIN [CC percents 3-6 to 3-12] ON [CC Coded].AssNO =
[CC percents 3-6 to 3-12].AssNO) LEFT JOIN [CC percents 4-
0 to 4-5] ON [CC Coded].AssNO = [CC percents 4-0 to 4-
5].AssNO) LEFT JOIN [CC percents 4-6 and older] ON [CC
Coded].AssNO = [CC percents 4-6 and older].AssNO;