BPMN, collaboration diagrams, call activities and message flows

Hi there,

I have an issue when modelling BPMN 2.0 in ARIS. Seems I'm in need of a workaround.

We model processes on two levels: a top-level, showing all subprocesses, and detailed models (collaboration diagrams) for all those subprocesses.

In order to be able to navigate down the hierarchy in ARIS, I replacesd the subprocesses by "call activities":

Validating it didn't go too well :-(

Seems like I can't connect a "messag eflow" to a call activity ("A message flow may only exist between events, subprocesses, and tasks"). The other message "This symbol is not alowed, please use another BPMN concept" I don't get. Maybe "Call activities"don't allow the "+"-symbol (but why does ARIS generate it then?)

But now the dilemma: all call activities above are detailled in collaboration diagrams themselves. Seems that I have two options:

1) replace call activities by subprocesses, but then I can't assign collaboration diagrams to them and therfore I cannot navigate. Replacing collaboration diagrams by "process disgrams" would mean loss of crucial details.

2) delete message flows on top level, effectively reducing the collaboaration diagram to a process diagram and losing detail in the overview.

So: how do I work around these issues? Anyone?

Kid Regards,

Jeffrey