I have a BPMN diagram (see below) with some errors that I can't seem to figure out. The diagram depicts the Produce Magazine Article Process, where the writer and Researcher are freelancers who work together to write articles for various publications.
Bigger version: BPMN diagram
There is a bunch of errors here, three of them are logical (two are related), one is BPMN syntax.
Let's start with the syntax.
The message is always a communication between two separate pools s it has to cross pool boundaries. In your case, you have depicted Freelancers as a single pool, so Send information, being between lanes but not pools is a syntax error. Before suggesting a solution though, I will focus on logical errors.
Time event is not used to show the fact that some time goes by between the activities. That is actually something natural in the process It is used to indicate that the flow of time is a trigger of the next action(s). For instance, 7 days after choosing a topic the Publication might contact the Researcher to check on the progress. That would be indicated by timed event. In your case, it seems that the flow continuation is triggered by passing messages so you should indicate it as an Incoming message event. You actually do that in 2 places, one that is obvious (Get article as a "result" of time event) and the second that correlates to a second problem.
The second thing that most probably is a logical question is that since we are talking here about freelancers, most probably Researcher and Writer are two separate entities, not one organisation as your current diagram suggests. If that is the case, you should have them represented as two separate pools. Then your message would be judged, but still rather than "Wait for information" time event you should have "Receive information" incoming message event (that is BTW the starting event for the Writer pool - similarly receiving Article request by Researcher should be handled by Incoming message event).
If you prefer to depict the Freelancer as one "organisation", then you should completely abandon the time event (as again you have used it as an indication of time passing and as I have explained earlier that is not how it should be used). You have a simple flow, where once Researcher finishes their job, it is passed to Writer who carries it over from there. In such case, you should have a simple action flow (solid line) between the actions themselves.
It is also a good practice to be consistent in using End events (and at least recommended - some BPM engines verify that) to always have an End even for every branch of a process. You are missing one or two, depending on how are you going to approach the Freelancers part. Similarly, you should have a Start event for Publication.
Below are the two options shown in the form of diagrams. Note that I also did some minor changes to handle the insufficient information case by Publication. Otherwise, they will be stuck forever waiting for the article to come.
Option with Freelancers as separate pools:
Option with Freelancers considered as a single organisation
