I have three forms:

Inventory (with among others 2 lookup Fields, Product_Class and Product_Sub_Class)

ProdClass (with one field, Product_Class) containing all unique ProdClass in ProdSubClass

ProdSubClass (with 2 fields, ProdClass and Product_SubClass) containing all valid ProdClass and Product_SubClass combinations

The Product_Class lookup of ProdClass works fine.

I want to filter the Product_Sub_Class lookup to only include records where

ProdSubClass.ProdClass = Inventory.Product_Class

But I have had no luck using the Set Filter choice in the form builder in Zoho Creator. Please Help