Structured Activity from Component Operation

[Tux]

Hi

I've added some "Components" to my project. The "Components" have different "Operations".
The "Components" should illustrate a C-source file. The "Opperations" are the functions of this module.

Now i want to use this "Components" in "Activity-", "Sequence-" and  "State-Charts". When I drag an "Opperation" to an "Activity-Chart" the tool draws an "Action" that is linked to the "Opperation". The problem is, that i would like to model the "Opperation" as a "Sub-Activity-diagramm". For that I would like to add the "Opperation" as "Structured Activity", not as "Action" to the diagramm. I can use the switch "Composite Element" on the "Action" to get a sub-diagramm, but then i do not have the "8" symbol that illustrates the sub-diagramm.

Is there a possibility to transfor the "Action" to an "Structured Activity"?

Thanks for yor help
Mike