compare two fields from same dataset in iif

hi,
This statement returns an "#error" on my report.
=sum(iif(Fields!current_fiscal_period.Value=Fields!fiscal_period.Value,Fields!shrink_dollars_positive.Value,0))
There is only one datatset for this report.
any clues?
thanks,
JustinGot it! I needed to Cint function
=sum(iif(Fields!current_fiscal_period.Value=Fields!fiscal_period.Value,
CInt(Fields!shrink_dollars_positive.Value),0))