Hello Jimmie,
I have split your comment on another question into a new question.
The Distinct Count aggregation function is only available if the Power Pivot Data Model is behind the pivot table. So, when you select the data for the pivot table, tick the box to Add this data to the Data Model, as in this screenshot:
Now when you build the pivot table, you will find the Distinct Count at the bottom of the list of options to summarize values.
This option will not show if you don't add the source data to the data model. It's easily overlooked and I hope that the Excel team will include this aggregation in all pivot tables soon.