I still don't understand your logic. I think you need to start again from
scratch with your problem statement.

Is it something like this:

If (SUM(B3:B999) equals OverviewE26) AND (SomeCell Jun 6, 2006) AND
(SomeCell < Jan 1, 2007), then ResultX, else ResultY.

1. What cell is SomeCell?
2. What is the formula (or value) for ResultX?
3. What is the formula (or value) for ResultY?

(Aside: This is probably NOT a VBA programming question, so should be
posted in the Worksheet.Functions newsgroup.)
--
Regards,
Bill Renaud