Counting logic

Hi all,

I'm tying to count in ssrs. I want to exclude one of my fields from my dataset. Basically I'm trying to could all of our tickets in helpstar, and exclude one of the queues. Here's what we have that's counting everything

=COUNT(Fields!REF_.Value)

Here's what I tried to write that will not save.

=COUNT(iif(Fields!Queue.Value<>"Enterprise Workflow",Fields!REF_.Value))

I get this error

The Value expression for the textrun ‘Textbox66.Paragraphs[0].TextRuns[0]’ contains an error: [BC30455] Argument not specified for parameter 'FalsePart' of 'Public Function IIf(Expression As Boolean, TruePart As Object, FalsePart As Object) As Object'.

Can someone help?

Thanks