Hi.
What Klaus said. What he means may be seen in this line from the dictionary:
The sort text form sorts by the ASCII value of each character. The sort numeric form sorts by number. Use this form if the sortKey consists of numbers.
The nature of the sortKey must be considered at all times. The point might be made a little more clearly, but just know that when sorting by the "length of each", one is sorting by a numerical, not a text value. I would post a user comment, but currently, as often happens, that feature is locked out.
Craig Newman