Stacked Column Charts with multiples Tables on Axis X

Hello,

I'm trying to create the following chart : I want to follow hours budgeted, hours done and hours left to do on a project.

For each of those 3 types of hours I want to add what kind enployees worked (exemple : Expert or Junior).

Here is the first step with the number of hours split among budget/done/to do :

But if I try to add the Category (=Expert of Junior etc...) I get this

I have tried to add the Category in the Legend but I can't.

It works if I only keep one type of hours like the budget. 

What am I doing wrong ?

Thanks in advance