The index is not sorted by itemNo.
It is sorted by date.
So you dont have an index on data sorted by itemno.
Imagine a phonebook sorted by Lastname, Then by firstname, then by address.
Your index will be (surname,Firstname,Address)
So I cannot search based on address because the phone book is sorted by surname, it is only possible to search by address if I already have the surname and firstname.
Same thing here.
Your phone book is sorted by date, then by ID then by number and not by ItemNo /Address, as an analogy.