I'm trying to use vlookup to give me a summary of some number throughout a
workbook. It has to sum across about 25 worksheets. not all worksheets have
the date I'm looking up so I will need to set the range_lookup to true so
that it will add the last inventory count before my specified date. I can
use the following on a small amount of sheets...but when I try it on the
large number of worksheets, it ultimately gets messed up.

=VLOOKUP(B6,Adams!$A$12:$D$100,2,TRUE)+
VLOOKUP(B6,ARCHIES_CORNER!$A$12:$D$100,2,TRUE) +
VLOOKUP(B6,BARN_YARD!$A$12:$D$100,2,TRUE) +
VLOOKUP(B6,BEAVER_DAM!$A$12:$D$100,2,TRUE) + VLOOKUP....etc

Any suggestions? SUMIF doesn't seem to work because of the date issue.