I've got the following piece of code which exectues within no problem
SELECT (
CASE WHEN
(SELECT DateDiff (Day, (
SELECT ChildDOB1 FROM MatterDataDef Where ptMatter = $Matter$),
GETDATE()))>6574 THEN '(over 18)'
ELSE '(' + ChildDOB1 + ')'
END)
FROM dbo.MatterDataDef WHERE ptMatter = $Matter$
Howeveer, when i attempt to wrap the code in brackets (so i can use it as part of a longer equation) i get the following error 'Conversion failed when converting datetime from character string'
any help appreciated :)