inside the central Square is supposed to have the attribute , and everything outside it the attribute , i.e. "not-".)
You had better adopt the rule to make mean the Attribute which occurs in the Middle Term or Terms. (I have chosen as the symbol, because 'middle' begins with 'm'.)
Now, in representing the two Premisses, I prefer to begin with the negative one (the one beginning with "no"), because grey counters can always be placed with certainty, and will then help to fix the position of the red counters, which are sometimes a little uncertain where they will be most welcome.
Let us express, then, "no nice Cakes are unwholesome (Cakes)", i.e. "no -Cakes are -(Cakes)". This tells us that none of the Cakes belonging to the -half of the cupboard are in its -compartments (i.e. the ones outside the central Square). Hence the two compartments, No. 9 and No. 15, are both 'empty'; and we must place a grey counter in each of them, thus: