Error handling and message constructing problem

Hello, I am unable to solve the following problem: In my long running orchestration in a parallel action shape I receive three different correlating messages from three different ports. Because of the possibility one of the messages could be missing I put this parallel action shape into a scope and added error compensation, catching a timeout exception. The problem is: The moment the catch block starts, no existing messages can be used to trigger mapping. In the compensation block I construct an XML message with a simple string in it. Normally I use a transform shape for mapping. Because of the missing message at this point I’m forced to use message assignment, but I can’t seem to get it to work. No matter what I write, when building the project I always get an “Unconstructed Message”-error even though I did construct exactly the message I was trying to modify (write a string into the only existing node).

This seems like a simple problem, but I just can’t get around it. Can anyone help me with this ?

Thanks in advance, Michael