Nested regions not allowed?

[macsux]

Scenario:
I have activity diagram
On it I have activity
Within activity is an expansion region
Within expansion region is a number of actions
Some actions are within Interruptible Region

Now if you look at the project browser, interruptible region was place on the activity level. If you try to add it as a child of expansion region, you get not supported message. Is this a limitation withing EA, because after checking UML specs I haven't found any such limitation?

[KP]

Looks like a bug to me. Please report it to Sparx Support. Thanks.