Tricky test

I got a contact on internet for an opening position. It was really weird because I posted an advertisement on a site 2 or 3 months ago to look for a job in a city that it's located in the center of my country, and last week I received an email with a problem to solve, I tried to do it but I couldn't solve it because of the complexity. A week later I received another e mail from the same guy and he seems a kind of desperate to find a guy to hire. I asked for more information and he gave me his phone number, I called him and talk for 15 minutes about the job and the requirements. Then he sent me another problem.
I checked it today and try to solve but for me there are no enough data to solve it. And apart from that the problem says that I need to specify the data that I don't have, and I don't have any idea on how to do it. I think that's too tricky, in fact he commented that nobody has passed the tests.
That job position is my ideal job so I hope I can get it.