I have a worksheet that is looking up data in other worksheets and summing
ranges by using the following formula:

SUMPRODUCT(--('Vend Sls Act'!$B$5:$IV$5=Worksheet!$C$8),--('Vend Sls
Act'!$B$5:$IV$5<=Worksheet!$D$8),'Vend Sls Act'!$B19:$IV19)

This is working great, however, I would like to be able to incorporate a
lookup to where the 'Vend Sls Act'!$B19:$IV19 piece looks up the vendor name
on the main page and returns the summed up data from the reference page. Any
suggestions? Thank you