Why keep getting this "Selected data can't be charted." Error in Dashboard loading a Row Report?

What I intended to do is super simple: bring two sheets into one Row Report and do a simple pie chart on the status field.

-> Source Data: two sample sheets A&B have exactly same fields.

and the status is a dropdown list with single value

-> The roll up row report, only picked the status field from the two source sheets.

-> then from the dashboard, add data from this report

Can't the Dashboard just load the data and do the pie charts by counts? Did I do anything wrong here?

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