A Puzzle: Increasing Education and No Mobility

In recent days some seemingly solid articles/posts have reported the following:

• over the past 40-50 years the average American has gotten more education (i.e., more people graduating high school, more people going to college, more people graduating college, etc.)
• over the past 40-50 years the added income attributable to education, the education "premium", has increased.
• over the past 40-50 years the earnings of the average American is no greater than his/her parents.

My knee-jerk reaction is that if the first two are right, the third can't be right.   There must be something else which I'm missing.