I have to send out a template to 160 different managers, and I need them to fill in their particular entity's unique number, which in turn will force other cells within the workbook to return a value (i.e., name of entity and location using VLOOKUP). The problem is that sometimes the managers do not read the instructions or forget to fill in the requisite areas of the workbook. Is there a way that I can force them to fill in a certain cell such that a pop-up window will appear to indicate they haven't filled in enough information or even closing the file will trigger an error message?