The background: earlier this week my own laptop broke down. So I had to borrow a laptop, what fortunately I could borrow from one of the presenters (thanks Guido). The thing is, though, that it runs on Ubuntu 12, so I ran my VM in VirtualBox 4.3 on Ubunty. Now actually that should not be of any difference, but it is really the only difference between my configuration and all the others (who all probably run on Windows).
When I create a bpmn process in Jdeveloper, I get this:
So apparently jDeveloper does not like the names it generates itself. Actually it turns out not to be the names in error, but the ids of the activities and events.
I struggled half a day with this, importing a new VM, since the suggestion was that I got a corrupt one and try it there. In the end I compared the bpmn file (found in the processes sub folder of the project) with the given lab-solution. And I found out that jdeveloper in my configuration generates Id's with a dash and a number that is one digit longer that those of the bpmn files in the lab-solutions.
The simple solution for this, be it very inconvenient, is to create your process, add all the necessary activities, but don't bother the implementations or even the names. Then close the application in JDeveloper. It's not enough to just close the file, since JDeveloper apparently keeps the file as XML DOM tree in memory. Then open the bpmn file in an ascii editor like notepad++ (windows) or gedit (linux).
You'll see enties like this:
<scriptTask isForCompensation="false" name="ScriptTask" id="ACT-10244072768044">
Search and replease all occurrences of 'ACT-' to 'ACT' and 'EVT-' to 'EVT'.
Then when you re-open the application and bpmn process, the activities are valid.
You see that the Script task gets a name according to it's Id. This is because there is another file in the root of the project, named after the process but suffixed with 'Documentation.xml'. Like 'ActIdTestDocumentation.xml'. In this file the actual names, documentation in different locales are placed. But you don't have to bother about that. When you change the name of the activity in jDeveloper the old name with id is removed of that file and the new name is added.