While working on a sales rep sheet I noticed that when you filter a table in
your chart some of your functions are not recognized even though youre still
referring to the same cells. I dont know why this happens and am hoping for
some help.

Ive provided two screenshots below. The first one shows what happens when I
sort the Grade Table from Z - A, and the second shows what happens when
sorted A - Z. The latter works perfectly, but Im just curious as to why the
other does not?

http://img148.imageshack.us/img148/2575/filter1w.jpg
http://img638.imageshack.us/img638/2818/filter2.jpg