Filter in Query editor with parameter

Hello,

For simplicity sake I'm going to explain the problem in an example scenario.

All the data from different company's is stored in one database (MySQL).

Each company has its own salesmen.

Goal: 

First a parameter needs to be given that equals one of the company's names.

Then you can only see data from that particular company in the data tab. So that data from other company's cannot be used when making visualisations.  

What I tried:

1. Made the relationship between Company and salesmen
2. opened power Query editor
3. set a filter on the company name base on a parameter.  Now I can only see the one company equals the company's name (1 row in the company's table).

Expected outcome:

        only data from the one company (in this case "Belfius") can be accesed when making visualisations.

Actual outcome:

 I can still see data from other company's.

I tried to explain it briefly and I hope that you an idea what I'm trying to achieve. If you have any further questions please ask.

Cheers,

Vincent Neuts