As I suppose from your screenshot you don't use tables. Your Products list looks like a normal range. I recommend to convert the range into a table object.
Here is a small tutorial for you to create your validation list with a name on column A. Right-Left-direction on your table must be noticed.Mine the left-to-right-direction. But it doesnt matter. Names are perfect tools to refer from whatever address it takes its content.
The table object is very good for changing entries on your list, because it is dynamic and adjusts automatically of what you select in the validation cell then.