External reference with variable workbook name

Hello everyone,

I'm referencing an external workbook and need part of the workbook name to be a variable with a SUMPRODUCT formula. The initial formula always need me to manually change part of formula each time, very frustrating.
My base formula is; =SUMPRODUCT(--('[_Budget 2014.xlsx]Jan'!$K:$K=$A$244);'[_Budget 2014.xlsx]Jan'!$L:$L)
I need "2014" to be a variable, with the new information pulled from a cell
within the referencing workbook.

What is the syntax for this reference? I've try with CONCATENATE to build-up the reference. Numerous combinations and have not had any luck:
- =SUMPRODUCT(--(concatenate(Setup!A1;P247;Setup!A2);concatenate(Setup!A1;P247;Setup!A3)))
- =SUMPRODUCT(--(concatenate(“&'[_Budget&”;P247;Setup!A2);concatenate(“&'[_Budget&”;P247;Setup!A3)))
- =SUMPRODUCT(CONCATENATE(Setup!A1;P247;Setup!A2);CONCATENATE(Setup!A1;P247;Setup!A3))

Variable are:
Setup!A1 = '[_Budget
P247 = 2015
Setup!A2 = .xlsx]Jan'!$K:$K=A247
Setup!A3 = .xlsx]Jan'!$L:$L

The ' seems to be part of the problem with the Concatenate formula. Don’t know how to solve it.
Does someone know what the problem is?

Thanks in advance.

indirect will help
but link source must be opened

Sumproduct work with closed files. I use concatenate to build the external link.
I dont know how to use indirect in this way. Does it still need to have the file open?