Get count depending on criteria using an expression.

Hi all,

I have a dataset that includes information on the compliance of users machines when being patched and am in the process of creating a report.
I need to be able to check this dataset for machines with 100% compliance rate but am having trouble doing this. (Effectively get the count of the rows that meet the criteria of =100)

I am hoping to display these figures using a chart so it must be done using an expression.

I've checked a lot of links on the internet and haven't found anything specific enough for me, can anyone offer any guidance on how to get the count when taking a criteria(=100) into account.

=Count(IIf(Fields!Percentage_Compliant.Value = 100, 1, 0)) - this just appears blank, does anyone know why?...

=Count(Fields!Percentage_Compliant.Value) returns 80 which is correct

Thanks a lot, I look forward to your replies!