VLOOKUP issues

on sheet 2 I have a table with columns a-o and rows 1-645. Various calculations get me to my end result in column "o"
Using 3 cells on sheet one, a drop down containing group names, a drop down showing the groups as selected and a cell to show the result.
The group is correct, the drop down shows the correct groups but I am getting an error when I try to show the corresponding value in column o.

This is what I am using...any help would save my hair
Thanks
=VLOOKUP(AH7, Sheet2!$A$2:$O$645, 15, FALSE)*C7

what error do you get?

#N/A means the value can not be found. Check that the lookup values are exactly the same. Leading/trailing spaces (or other invisible characters) is often an issue.