Tal rasha death mask upgrade

Hi so I tried to use upgrade recipe because It is exceptional version of the item,It did not do anything tho.
I've upgraded my tal rasha belt just fine,makes me wonder where could it go wrong?
I used perfect diamond+ko+lem

 

As far as i know you cannot upgrade set items, that recipy is for uniques only... Are you sure u did upgrade ur belt?

 

I think not,i just confused the name 'cloth belt' with actual item type that is mesh belt

So you are right,i can not upgrade set items.