3Red interview questions

Phone screen asked some general questions on my past projects, WPF use, and mutlithreading. Interviewer seemed friendly enough and said the company was a small company looking for out of college candidates with some C# experience. They requested a market data displaying application.I handed in the assignment to them and the next day got an instant decline. The assignment was done to specification and standards. No questions or feedback on my work, why the decline or even a phone call to better understand some code choices. Everything was done to specification and standard using WPF in an MVVM design. It was a complete and utter waste of my time to have no feedback at all.