I get #NUM! In Access in a report when I'm trying to calculate a %.

SalesTY - Sales LY = DIFF
Sum(SalesTY) - sum(SalesLY) = TOTDIFF
These are Names I put on the field in the report.

TOTDIFF/TOTLY gives me #NUM!

I have IIF Iserror, and that works in many reports, just not this one.
Thx