make sure that both workbooks are open when you create the formula like =LEN([testsheet.xlsx]Sheet1!$C$7) where testsheet is the name of your XYZ book. if you then close your workbook and look again at your formula in your open book/sheet if may read something like this =LEN('C:\Users\Don\Desktop\New Briefcase\[testsheet.xlsx]Sheet1'!$C$7) where I am using Excel 2013 and I have one sheet closed and one open. excel is telling the open sheet where to look because they are not in the same directory right now. depending on your version, and your set security level you may not be able to update your formula in your open book, with the other one closed. most of the newer versions will allow this. try again and I hope this helps . ~DR