countif using range in conditional formatting

Several inventory spreadsheets in a workbook, a new one added each week w/ current inventory. Column A=item numbers with a range name. I then use conditional formatting to highlight all cells containing new items. ie.. new arrivals and did not exist in previous week's sheet.

I do get some cells to highlight correctly and I thought it was working but then I find SOME of those item numbers do exist in the previous weeks sheet. So..... what have I done wrong?

Very simple but oh so elusive!
So many questions and so many helpful people here that I can't seem to find this.
Thank-you in advance.