Sorting by Ascending and Descending Order

Question

Hello,

 

My program uses a list view to keep track of some information. There are multiple columns and I would like to be able to click the column header and have it sort in ascending order. If I click again, it changes to descending order.

 

I have used the following resource, but when I click on the column header, nothing changes.

 

https://support.microsoft.com/kb/319401

 

Where is my issue?