Hi. Given the following Sumif formula:
=SUMIF(Data!$F$7:$F$1100,$A16,Data!$AA$7:$AA$1100)

Column AA is January results, with AB February, AC March, and so on. Above
each column header (for example, in cell AA1) I have the number of the month
(1,2,3 etc). Then I have a pulldown validation list in A1 with 1 through 12
in it. The goal here it to choose a number from the pulldown and have the
formula update and sumif the proper column. It doesn't seem like that
complicated of a problem, but I can't figure it out! Thanks for you help!