I have stock report files for every week named as
1) Stock Repo-01, 2) Stock Repo-02, 3) Stock Repo-03 and so on where 01, 02 indicate week numbers

Every report file has separate sheet for days and Summary Sheet showing total transactions of all products every day .

Summary Sheet has Current Report no. in cell E1 and date in cell F1
col-A>Part No., col-B>Product, col-C>Opening Balance, col-D> Recieced Qty. col-E> Issued Qty. col-F> Closing Balance

quantities in column F from file <Stock Repo-01> are to be copied in column C of successive file <Stock Repo-02>
the formula in cell C5 is =’[Repo-01.xlsm]summary’!$F$5
now I want this formula to take no. 02 from cell E1 (where E1 contains current Report no. that is 02) so that formula will be =’[&”Repo-“(E1-1).xlsm]summary’!$F$5
but its not working, what changes are required in formula to work.
Else can I use Lookup formula having similar changes in filename as above.