VBA code to have pop up message when opening excel file about expiring due dates

[sdrigny64]

Hi, i know this thread has been asked a lot of time... But i still cannot make it work. I have an excel file about equipment and all these equipment have expiring date when they will be send for recertification. I did create already a conditional format for all these items with different colors when reaching less than one year, 6 months before recertification dates. Now what i want is having a message popping up when these items are 1 month to reach recertification date. I have 11 sheets in my workbook and all the recertification dates are not at the same positions on all sheets. i have attached my excel file.