That's fine - this:
=INDEX('C:\[Book1.xls]Sheet1'!$C$3:$F$11,2,2)
and this
=indirect("Book1.xls!"&"D4") (where D4 is assembled in some way)
achieve the same, but one works when book1 is closed - and, as it's not volatile, is more efficient.

Am I missing something?

CC