Exactly what I want to do is lookup/update on column "AF" on the active
workbook / HSI sheet matched on optical TX column "AI" to the 98th
percentile workbook/History sheet column "L" which is also optical TX column.
For those matching records I want it to update the active workbook column
AF weekending 7/7 column of "AF" from column I.

This is what I have right now but it isn't matching anything to do the update.

=VLOOKUP("50.00",I:'[07-0714 98th Percentile.xls]History'!$I$4,3205,HSI!)

thanks,