Error in Excel

I created a form that allows our CSR reps to enter in a set of fields and
based on the sequence of answers, a calculation in excel yields the Lead
Level (whether it should go to a Jr. rep or a Sr. rep) - I have programmed in
VB to pull the Lead Level back into a field on the form so the user doesn't
have to ever see the workbook (for security purposes).

It appears that the file can be opened, and updated but when they click
submit, the calculation in excel does not work properly. i created the form
on my 2007 computer but saved it as a 95-2003 version. Anyone in the office
who has Microsoft 2007 can use the fomr successfully. but anyone with 2003
cannot.

Please help!!!

Here is the formula - it is referencing a sheet named "Matrix" which is in
the same workbook, but hidden from users. The data that is entered goes into
Columns A-F and the calculation is placed in Column G:

=INDEX(Matrix!G:G,MATCH(A2&B2&C2&D2&E2&F2,
Matrix!A:A&Matrix!B:B&Matrix!C:C&Matrix!D&Matrix !E:E&Matrix!F:F,0))