Job Destination File Name Using a Date Expression

 According to the BIP publisher documentation, 4.9.2 Defining a Destination File Name Dynamically Using a Date Expression.  I should be able to use supported date expressions to create a dynamic file name for output:

Expression Description

%y

Displays the year in four digits: Example: 2011

%m

Displays the month in two digits: 01-12 (where 01 = January)

%d

Displays the date in two digits: 01-31

%H

Displays the hour in two digits based on 24-hour day: 00-24

%M

Displays the minute in two digits: 00 - 59

%S

Displays the number of seconds in two digits: 00 - 59

%l

Displays milliseconds in three digits: 000 - 999

However, when I create a job and set the file name to "my_file_%y%m%d", the report that is attached has the file name "my_file_%y%m%d.xlsx" literally.  I have tried other formats.