Problem in relationship between tables

[LearnMeExcel]

hi

i need help in this issue
i have 4 Tables:
1. SalesDB : contains All Data for My Invice --> i have column named "CustCod"
2. CustomerDB : all Customer info more than 15000 Rows --> i have column named "CustCod" , i connect SalesDB with CustomerDB by this Col
3. GiftDB : contains the custome who get gift from our SalesRep "some customer get more than 1 gift, that is mean more than one row for him " --> this table Conect with CustomerDB
4. TabDB : contains the custome who have Tables for our Products"some customer get more than 1 Table, that is mean more than one row for him " --> this table Conect with CustomerDB

what i work on, i want to know the customers who Get Gifts, and the Custome who have tables
in CustomerDB i add new Column to make Calucalted column by this DAX
=RELATED(GiftDB[CustCod])
but i get Error " The Column 'GiftDB[CustCod]' either doesn't exits or doesn't have relationship to any aviable in the current context"
============
i reviewd all relationship between tables it ok and all of this relationships are active

what is my problem
or how i can't solve this issues to get the customer who have gifts or table
any idea please

 

[LearnMeExcel]

No idea
By another way
If I use normal excel I will use COUNTIF
=if(countif(giftdb[cusCod],CustomerDb[activeCell]),1,0)

How I can make same formula in customer table to know if have gift

 

[PentaGalCXO]

If I understand your layout correctly, your formula won't work because the relationship is in the other direction. I would approach the problem by adding 2 columns to the CustomerDB:
GiftCount:=calculate(countrows(Giftdb),filter(Giftdb,Giftdb[CustCod]=CustomerDB[CustCod]))
TabCount:=calculate(countrows(Tabdb),filter(Tabdb,Tabdb[CustCod]=Customerdb[CustCod]))

Note that these formulas do not leverage any existing relationships. They are evaluated when the model is loaded (not on user slice/dice) thus could be sluggish to load, but fast to pivot on.

Depending on your reporting needs you can now pivot on the CustomerDB table, or first create another column in CustomerDB that acts as a flag (if(GiftCount>1 && TabCount>2,"GoodCust",blank()) or something similar.

This kind of approach bothered me in the past as I am very much a star schema traditionalist, with calculations in the fact table and filtering by dimensions - and this approach is the opposite. Long story short... I got over it...