Dropdowns Based on 2 Criteria

I have been successful in creating a dropdown based on 2 criteria. Here is the formula I used: =OFFSET(Items!$E$10,MATCH(1,(ItemsCategories=G7)*(ItemsSubCategories=H7),0)-1,0,COUNTIFS(ItemsCategories,G7, ItemsSubCategories,H7),1). This formula works, and the dropdown is working. My problem is, every time I close the workbook it seems to reset, and when I open the workbook again the formula does not seem to work. So I go to the data validation for the cell which contains the dropdown, click on the box "Apply these changes to all other cells with the same settings', click OK, and it works again. Without making any changes to the formula itself.

Can anyone explain this?