In Yaoqiang XPDL/BPMN Editor, Pools and Lanes are implemented by swimlanes,
the root swimlanes are treated as Pools and swimlanes within other swimlanes are treated as Lanes,
all the activities(tasks, events or subflows) must be within a Lane.
So you need drag and drop at least one Pool into diagram, then drag and drop at least one Lane into the Pool.
After these steps you can drag and drop any activity into the Lane.
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In Yaoqiang XPDL/BPMN Editor, Pools and Lanes are implemented by swimlanes,
the root swimlanes are treated as Pools and swimlanes within other swimlanes are treated as Lanes,
all the activities(tasks, events or subflows) must be within a Lane.
So you need drag and drop at least one Pool into diagram, then drag and drop at least one Lane into the Pool.
After these steps you can drag and drop any activity into the Lane.