Since you had given no detail, I suppose you can´t send any message at all. Just keep it simple in the beginning, like using "throw message" in process 1 and "start message" (green icon) in process 2. Do not use any variables this time. Just understand how it works.
Then you can add complexity (correlations and correlations) but be aware, there is a bug when using a "Boundary Catch Message" (nothing happens).
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