Help with slicer week ending dates

[muzzy]

I have a pivot table with week ending day on it 6-Jan-18. But when I make a slicer for them they are not in descending order it is mix up. can someone help6-Jan-18
13-Jan-18
20-Jan-18
27-Jan-18
3-Feb-18
10-Feb-18
17-Feb-18
24-Feb-18
3-Mar-18
10-Mar-18
17-Mar-18