adding empty cell only if nothing else is entered in referring cells

Hi

I need to enter an empty "total" cell (text) in a "total" tab if the other cells are empty, otherwise enter a dash "==="

refer to cell D29, D30 & D31 on the attached

I know this formula is incorrect but hopefully it gives you the gist of what I'm trying to do

=IF((Monday!I30)and(Tuesday!I30)and(Wednesday!I30)and(Thursday!I30)and(Friday!I30)="","","=====")

many thanks in anticipation