I am trying to pull information from another workbook and only get an error
when the other workbook is not open. When the other workbook is open, all is
well.

Here is the formula.
=IF(COUNTIF('[EP01Jan1-2-4-07.xls]Eff'!$AH:$AH,CONCATENATE($C3,$B3,$C$2))=0,"n/a",SUMIF('[EP01Jan1-2-4-07.xls]Eff'!$AH:$AH,CONCATENATE($C3,$B3,$C$2),'[EP01Jan1-2-4-07.xls]Eff'!$Z:$Z)/COUNTIF('[EP01Jan1-2-4-07.xls]Eff'!$AH:$AH,CONCATENATE($C3,$B3,$C$2)))

Looking for any help I cna get on this.
Thanks