Not sorting correctly

I have the filter on in my sheet and below is my code so far.

For some reason that I cannot figure out, it is not sorting the column F to descending, it doesn't look like it's doing anything.

HTML Code: 

I want the data to sort descending and then I will set n to the last row with data in column F, so that way I can set the row source of the listbox from n to LR and that should be all the empty fields in column f


thanks for any help

typo

I meant it is not sorting column M to descending order