Hi, I have an array formula to calc interest (another for principal). It works perfectly in Excel for PC 2010, 2007 and for Mac Excel 2011. HOWEVER, it doesn't seem to work in Mac Excel 2008. The formula doesn't have the array {} brackets around it when the file is opened and you can not activate it by pressing "Command + Return".

This is the formula
=-1*SUM(IFERROR(IF($F241:G241<>0, PPMT($F244:G244, G234-$F234:G234,$F242:G242,$F241:G241)),0))

Any and all help appreciated. We use PC and client uses MAC 2008 and this affects the entire worksheet.

Thanks very much....