Hi there,

This works for me:

=SUMPRODUCT(('found-data'!$A$2:$A$10219'found-summary'!$A6)*('found-data'!$A$2:$A$10219<'found-summary'!$A6+1)*('found-data'!$B$2:$B$10219='found-summary'!C$4)*('found-data'!F2:F10219='new
interface'))

But when I added in the final clause below, it breaks:

=SUMPRODUCT(('found-data'!$A$2:$A$10219'found-summary'!$A6)*('found-data'!$A$2:$A$10219<'found-summary'!$A6+1)*('found-data'!$B$2:$B$10219='found-summary'!C$4)*('found-data'!F2:F10219='new
interface')*('found-data'!F2:F10219='new interface'))

I've been playing around, and reviewed Excel's 'common formula
mistakes' tips, but for the life of me can't figure out what the
problem is. Any ideas? I don't imagine I'd need to provide any sample
data to debug this, but if it would be helpful just let me know.

Thanks!
Jeff