I'm trying to to count the number of rows within a group that meet a certain criteria in SSRS. 

In my Tablix; i have a category group. Within this category group there is a Create\_date column. I want to count the number of rows within the group where the Create\_date is within the current month.

```
=SUM(IIF(ReportItems!Inital_Date.Value > 
DATEADD(mm, DATEDIFF(mm,0, Today()), 0) 
AND ReportItems!Inital_Date.Value > 
DATEADD(dd,-1,DATEADD(mm,1,DATEADD(mm, DATEDIFF(mm,0, Today()), 0)))
, 1, 0))

```

I've also tried to specify Fields! instead of ReportItems!; I think i need to properly specify the scope of the group perhaps?

This gives me an error:
*Aggregate functions can be used only on report items contained in page headers and footers.*

I've included an image of my tablix layout as well.

[![Tablix Layout](https://i.stack.imgur.com/XUGB5.jpg)](https://i.stack.imgur.com/XUGB5.jpg)