Glad you got it to work.
If you have not done so already you may want to conditionally format the field also using the same logic, like punch it it in red ink when they screwed up.
as an example
right click on the formula field
select format field
select font tab
click on the formula box next to Color
add your condition here as
if trim({JrnlHdr.QuoteIDForSales}) = "" then crRed else crBlack
You can use all sorts of conditional changes to really make items stand out
Edited by DBlank - 27 May 2010 at 12:09pm