HI FD,
Thank you.
Can I tease out exactly what you want as a result because in Excel there is a difference between zero, null/blank and #N/A.
One of the problems with your approach is that ISBLANK sometimes only looks at the first cell in a range and does not check the subsequent cells.
If you want to check for blank/null values rather than zero or #N/A then this should work in cell B6:
If all the cells in B3:B5 MUST have values:
IF(COUNTBLANK(B3:B5)>0,"",SUM(B3:B5))
HTH
EG