Automatic invoice charges based on date selection

Hi guys, would anyone be able to look at the attached workbook for me and tell me why my formula on A23:A30 isn't working?

It's very curious as it's exactly the same formula as Alf & Newdoverman helped me with above, just on a different workbook. Everything is the same as before as far as I can see - not quite sure why it works on one workbook but not on another?

Thanks!

https://www.dropbox.com/s/me751u7mq2...20Invoice.xlsx

I've done something stupid, and I'm not sure exactly what!