Issue relating four tables

[paliman]

Hello everyone.

First of all, I am new with PowerPivot (in fact this is my first attempt) and I got stucked too quickly

Ok, let´s go to the problem:

I have four tables with these relevant columns:

Table: Prod_Master
Product_ID (unique items)
Product_Desc

Table: Inventory
Product_ID
Quantity

Table: Direct_Cost
Product_ID
STD_Cost_Materials

Table: Indirect_Costs
Product_ID
STD_Freight
STD_Labor
STD_Overhead

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My goal is to value my inventory and to do that I have to calculate:

Quantity * (STD_Cost_Materials + STD_Freight + STD_Labor + STD_Overhead)

This for each Product_ID, and then get the sum of all IDs

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I have created these relationships:

Table – Related Lookup Table
Inventory[Product_ID] – Prod_Master(Product_ID]
Direct_Cost[Product_ID] – Prod_Master(Product_ID]
Indirect_Cost[Product_ID] – Prod_Master(Product_ID]

I hoped that all these tables were related to each other through the Prod_Master table, but they are not; i.e., if I want to add a calculated column in the Inventory table with

=related(Direct_Cost[STD_Cost_Materials])

It returns the following error:

The column 'Direct_Cost[STD_Cost_Materials]' either doesn't exist or doesn't have a relationship to any table available in the current context

I am only able to relate any table to the Master table and in that direction only.

What am I missing?

Thank you all in advance