Slicer and timeline issues when having dates as column headers in table|Dashboards & Charts|Excel Forum|My Online Training Hub

Hi, 

I am a new user of this page, found after watching some youtube tutorial videos, which I enjoyed a lot. 

Now I am trying to make a forecast model. And I have met some issues. 

I built it as a matrix, with projects as rows, and months(periods) as columns and input is the forecasted sum. 
Now I am making a dashboard, and I by using the pivot tools, I was thinking about making a timeline or regular slicer, where I choose the months I want to look closer at. 

I have issues because I am not able to make a slicer based on headers, only on the input in the table. Does anyone have a better solution for how to build this or how to solve this issue? Also when creating a pivot diagram for the data, it does not show naturally with dates along the x-axis, as it does when creating a diagram from a table. 

In advance, thanks for any responses. 

Regards Thyra