Ignore selection on all tables except for one

[ElsKnockaert]

Good morning

I'm new to Qlik and have come across an issue I can't seem to work out.

I have a variable vScopeCust that should result into, for example, the amount of customers that are selected by use of fields in the tables Customer or Customer Visit Times. If there is a selection on other tables, like order or visit, this number should remain unchanged.

definition :   $(='[' & Concat({<$Table =- {'Customer','Customer Visit Times'}>}$Field,'],[') & ']') 
usage:            Count({$<$(=vScopeCust)>} Cust_Internal_Id)

This seemed to work with other tables but not with the table ND_Period. Whenever a date is selected from this table vScopeCust seems to take it into account. So when I select a value of ND_Year_Month (field of table ND_Period), the expression Count({$<$(=vScopeCust)>} Cust_Internal_Id) returns a different number than before. It changes from 837 to 567. 

However when I try to collect all possible values containing to the customer table for these selections,  I do receive the right number, 837 clients. This is not a good solution though as there are a lot of fields in the table Customer and this variable is used a lot throughout the sheets.

Count({1<Cust_Territory=P(Cust_Territory), Cust_Chain=P(Cust_Chain), Cust_Active=P(Cust_Active)>} Cust_Internal_Id)

Now for my question: How can I make my variable vScopeCust work with the table ND_Period so that when a period from this table is selected, vScopeCust ignores it, just like the other tables?

Any help would be appreciated!

[Vegar]

Could it be that you are having active selections in the $table or $field? Override these by using a full set in your variable. 

 $(='[' & Concat({ 1<$Table =- {'Customer','Customer Visit Times'}>}$Field,'],[') & ']') 

[ElsKnockaert]

Thank you for your reply!
There are some active selections on fields, screenshot inclosed.
But with the alteration to include the full set, I still get 567 customers instead of 837.