The Add Data Column Activity is used to add the Columns and not the Column Values.
Maybe by Debugging and Checking out the Contents of the Datatable you’ll be able to understand the populated columns as per your process.
Just to Inspect, you could use a Write Line Activity and Check out the number of Columns that you have added to the datatable like below :
Also, If you could explain what is yout Input data and How you would want the Output to appear, we could provide you with better suggestions to achieve it. Screenshots/Files would be helpful.