Attempt to fetch data from another file using OFFSET() failed

Hello Sir,

I tried to use the OFFSET() function to fetch data from another file, but resulted in error. To put it using a simple example, Book1.xls tries to read data from Book2.xls as in cell A1:

=OFFSET([Book2]Sheet1!$A$1,ROW()-1,0)

When file Book2.xls is open, this worked perfectly. But it got all error values if the file is closed.

Why this happened?

Interestingly, the INDEX() function works well, even if the source file is closed