You're correct. Autofill does not work on filtered lists.

You could sort the list by your criterion, fill in column B, then sort it
back.

Regards,
Fred.

"alibaba" wrote in message
...
Let me make it simpler.
column A stores the exam subjects that I am going to filter. I found that
after applying the data--filter--autofilter

(with some creteria) on column A, a certain subject(say English) is
filtered. Then I try to use autofill in column B to

assign seat number to the students(001, 002, 003,..). However, I cannot
fill
in the series. Can anybody help me?