Advice for my software testers, though it applies in many other parts of life as well:
Don’t just say “this doesn’t work.”
Use something like “This is what I did, this is what I expected, this is what I saw instead, here are the things I’ve tried, and this is what I think is wrong.”
Optimally, follow with “and here’s how I think it can be fixed.”
It’s important to Learn Why Things Work.