In a workbook I have 36 sheets, one for each month from January 2012 to December 2014, named Ja12, Fe12, Ma12...No14, De14.

All sheets are alike. In Column A (A5:A20) I have customer numbers, In column Q (Q5:Q20) I have sales totals.

In an additional sheet, I like to be able to type a customer number in D9, and in F9 have returned the total sale for te customer over the 36 months. In this sheet, column A I have a list of all my 36 sheets.

This formula Works, if I just want to Count

=SUMPRODUCT(COUNTIF(INDIRECT("'"&A1:A36&"'!a1:a20" ),D9))

but I can't get it to work when I try to use SUMIF in stead of COUNTIF. No matter what I try to put in the last argument it doesn't Work. Either it returns an error or a zero, like when i try with

=SUMPRODUCT(SUMIF(INDIRECT("'"&A1:A36&"'!a1:a20"), D9,INDIRECT("'"&A1:A36&"'!q1:q20",)))


Any ideas?

Jan