Vlookup function not updating when i insert a col.

Hi,

Here is my situation. I have two sheets. One called "Roster" and one called "final". On the final sheet i have cols for each question on the final exam. I also have a total col which sums up the pts for each question.

On the "roster" sheet. This is kinda like a summary sheet. On this sheet i use a vlookup (shown below) in the cells which are supposed to reference the cells on the "final" sheet for the total pts.

=IF(ISERROR(VLOOKUP(A2,Final!$A$2:$Q$68,15,FALSE)),"NA", VLOOKUP(A2,Final!$A$2:$Q$68,15,FALSE))

Here is my problem. Currently the total pts col on the final sheet is 15 cols over. However, if i add another col, which i would do if i added another exam question, the above formula (which is on the "roster" sheet) does not update now to "16"........it is staying at "15" and i dont know why. I thought it would update if i inserted another col on the final sheet.

Can anyone help?

If you need more info just let me know.

Dave