I have created two flowgear workflow for demo purpose and understanding how to work flowgear SubWorkflow.I have created two flowgear workflow ex.below is the link:
1)Test1:http://flowgear.me/s/ovY8mH9
2)Test2:http://flowgear.me/#s/20vD6P6
In Test1 workflow drag one SubWorkflow Node and set appropriate property.
In workflow id property i have set Test2 workflow id. When i run Test1 flowgear workflow the SubWorkflow gives the following error: Invalid Site or Workflow