Stacked bar charts are a powerful way to display comparisons between your data. Stack charts must contain Group By expressions.
Select the following option on the Chart type menu to display a stack chart.
Example
The viewlet below is located in the Sample-OrderTracking repository. It is searching for missed SLAs (service level agreements) and is presenting them in a stacked barchart grouped by name, location, severity, and time.
jKQL > Get the number of activities for the latest 3 days that did not meet 'SLA' group by location, activityname, severity, starttime bucketed by day show as stackchart