Are there any step by step directions for using the IB_LookupCombo?

I thought I had it, but ....

I have a lookup field that can take an integer 1..5, and a string that
is mapped to each of these values in a separate table (my lookuptable)

In a grid's query, I am displaying a field with the lookupnames using a
subquery.

main query (IB_QUERY1) (has an attached Dataset )
SQL:
SELECT T."ID",T."SHORTDESC",
( Select C."LOOKUPNAME"
from "TODOCAT" C
where T.CATEGORY = C."LOOKUPV") as LOOKUPNAME,
T.CATEGORY
FROM "TODOS" T


The only strangeness here is that the edit queries need the following
quoting:
update "TODOS "
set
shortdesc= :shortdesc,
category = :Category
where
ID = :OLD_ID

(This may be the problem and may be related to the tools I am using with
FIREBIRD to layout my tables)

Lookupquery
SQL:
select LOOKUPV, LOOKUPNAME
from "TODOCAT" C

Keylinks: TODOCAT.LOOKUPV=TUDOS.CATEGORY

KeySource = IB_Datasource1 (which is attached to query 1)

When I activate the second query, it complains that the keylinks are
invalid.


I must be missing something simple.

Thanks

Carl