Using spandex to start a trace, however cannot see the trace in datadog

I’m using Phoenix. I have one of the forms where the user signs up and I want to create a new trace for this. I’m using DataDog in the backend. To start the trace I’m doing the following

tracer.start_trace("user_sign_up")
tracer.start_span("validate_data")

# do some work

tracer.finish_span()
tracer.finish_trace()

However i don’t see this new trace in datadog. I can see the other traces included automatically by the Phoenix router, but I don’t see this trace.

Is this really all tracing-related code you have? I don’t think so, you probably also include some metadata or measurements, which in my recent experience are a common source of silent errors while sending to Datadog. Can you show the code related to that?