Daedalus is responsible for his son's death because he knew that wings he made were not yet proved to be safe and working. And his son, as a teenager Daedalus as a father should know that people in such age do not always follow their parents because they just do what they think is fun. And he could have just lived peacefully in the Labyrinth with his son
For me, Daedalus is not responsible for Icarus' death because he warned Icarus to not be near the sun or the qax on his wings will melt. It's Icarus' fault that he didn't mind his father's warning.