I have downloaded this function, but cannot seem to make it work. I need to
sum up 13 sheets using a vlookup reference (cell B13). This is what I used:

=SUM(VLOOKUP(B13,THREED(EUR:VGS!$B$12:$V$120),6,0) )

EUR:VGS are the sheet names. Each sheet in between has a different name. Is
my naming convention not going to work? Right now it only returns the value
from the first sheet (EUR) only.

Thanks
CM