Find subsectors that are cheap vs their own history

I tried this formula but got error. Any ideas how to make it work ?

FHistZScore("Aggregate(`SalesTTM/EV`,#SubSector)", 26, 2)

ERROR: Encountered error in Rule 5: Could not find uid 5433 in function Aggregate -- map size is 0

This works but it is less flexible:

FHistZScore("Pr2SalesTTMInd", 26, 2)