Indexing formula

Gretings, Gurus.

I am wiritng a script to enter a formula into a range of cells to lookup a value from another workbook. I am currently stuck on the formula.

Here is what I've tried, (and several variations), and I always get an #N/A, even though I know the number I am indexing is in the array I am searching.

=INDEX(A7,MATCH(A7,'[MB-NPR-5-10-10 (2).xlsx]MASTER'!$A:$E,0),-4)

What I am trying to accomplish is this, lookup the number in cell A7 against a list of numbers in another workbook, and return the value 4 columns LEFT of the number it finds. (The formula should look for the value in column E, but return the value in column A.)

I can't use vlookup, because the value isn't the first column, and I'm having a problem wrapping my head around the index formula.

Thanks in advance for any help you can offer.