The real question is did you check ?
As I said the sort works - I used your gallery to test it
in the attachments I sorted your gallery by views and by size both work perfectly.
First you have to be IN a category, not in the page that shows all the categories
Second the size is sorted based on the largest files size
in the first attachment it goes from 58k to 68k to 73k etc
If your goal is to simply ***** then Ill unsubscribe from the thread and let you continue.