Dynamic Named Range

I have a dynamic named range as follows:-

OFFSET([Employees.xls]Production!$A$1:$A$1,0,0,COUNTA([Employees.xls]Production!$A:$A)-1,12).

In MyBook.xls I have the formula INDEX(A1:B1,2), which I want to insert into the OFFSET function in place of the sheet name Production.

I say I want to because I can't get the syntax right! Can anybody help?

T.I.A.