New column returning always the same value on a virtual table

Hi there,

I have this table with project data, where each project lives on one row. I have several columns for each row, amongs them the beginning and ending date.

Table Sample

Expected Output

Error I am getting: 

So I basically need to create a virtual table where I add a new column with the total days of duration for each project. So I created this Dax code below, but when I go to check how the virtual table looks (creating a phyical table based on the code) I get the same duration for every project. It seems the code is not having a "row context" :

var current_project = SELECTEDVALUE('Project Table'[Project ID]) // current ID in the present row

var dates_project = calculate(countrows(DATESBETWEEN('Project Table'[Data Criação Project ID],SELECTCOLUMNS(filter('Project Table','Project Table'[Project ID]=current_project),"N",SELECTEDVALUE('Project Table'[Projecções Data Início])),SELECTCOLUMNS(filter('Project Table','Project Table'[Project ID]=current_project),"N2",SELECTEDVALUE('Project Table'[Produção])))))           // filters the initial table based on the current row project ID and then selects the Beginning date, and ending date. Finally I use countrows to count the number of days

var tabela_virtual = ADDCOLUMNS('Project Table',"@Total days",dates_project)))

Return tabela_virtual