If I run the query:

Code:
SELECT TO_DAYS( NOW() ) - TO_DAYS(date) AS ageing FROM invoice
Everything works fine (woohoo! ).

But if I add this WHERE clause:

Code:
SELECT TO_DAYS( NOW() ) - TO_DAYS(date) AS ageing FROM invoice WHERE ageing >= 60
Then it craps out (boo hoo! ).

Can someone point out my stupidity?