Count FieldItem value iif Multiple feild value is true

 I would like to count the values in a field if that value is true  also the count can only take place if the value in another feilds is also true and another value is false.

Something like this:

=Count(iif((((Fields!On_OQ.Value = "Yes") and(Fields!On_Hand_at_Max_or_greater="Yes")) and(Fields!ROP_ROQ_On_Hand___0="FALSE")), 1, Nothing))

I want to only count the values inFields!On_OQ.Value if this field is yes and the other two is Yes and False.

please help asap.