Graph of total count of category over time

[JoeCrozier]

I have a dashboard like this:

As you can see, you can use a slicer to affect dates, and when you filter the data to a date range, a Pie Chart will show percent of the total rows that have a certain category of sponsor type.

What I'd like to create is a graph kinda like this:

That shows those categories over time.  I've played around with creating a line graph and quick measure:

But when I pick any of the time intelligence quick measures and select the date to use it says "Only Power BI provided date heirarchies or primary date columns are supported" , even though the date column I pick is recognized as a "date". 

Any ideas how I could accomplish this? Ideally the timeline would go for several years and be grouped by months, and show at any given month how many of each type of sponsor there were.

[JoeCrozier · Accepted solution]

I figured it out.  The date column was somewhat incomplete and couldn't be a traditional heirarchy because it was missing dates.  I ended up extracting month and year into a new column and playing with it that way.

[Bifinity_75]

Hi @JoeCrozier possibly it is a "bug" in the relationship of the dates.
Do you have any relationship with this date?. Someting like this: