I'm using this in one spread sheet just fine:

=IF(ISBLANK(F2),NA(),E3+F2)

Trying to use this variation in another workbook and am getting the #name
error

IF(isblank ('Control Plan Results'!W16),NA(),'Control Plan Results'!W16)


Not sure why, I thought I had a type in the sheet reference so I copy and
pasted just to make sure. Any help would be great.

Derek