If the arrangement is

>! **ABC or BAC**

And 

>! Anna doesn’t state her information.

Then:

>! Since if **ABC**, B states C is not older than A and the configuration could be ABC, BAC, ACB for their minds. C states that C is not in the middle and the only possible configurations are ABC or BAC. This way they know C is the youngest however A and B’s position is not known.

Or

>! If **BAC** they will know C is younger than A and is not in the middle. This reveals his position. Although A would know B’s age B would not be embarrassed because he wouldn’t know this fact and for C it can either be BAC or ABC in his eyes.

Then

>! Zorro is a good logician.

Zorro is a not good logician if the youngest be:

>! BOB or ALICE because **ACB** means that they would work out A is the oldest if they were to work out B even if A doesn’t state her information- one has to know C is younger than A and in the middle to know B. For **CAB** there are insufficient clues for the position B. If **BCA** it has to be known that A is younger than C and C is in the middle but then they can deduce B is the oldest. Finally if **CBA** it means again A has to be known to be younger than C but still A’s position is not specified.