To Our African-American Bernie Supporters, Why Do You Think He Is Not Doing Better With African-American Voters, and What Should He Do to Do Better With Them?

I can't see what issue Hillary is stronger on with respect to African-American voters, and Bernie really needs their support. Can someone please educate me why he is not doing better with them on average? (I understand African-Americans don't all vote the same way, and have different opinions from each other, but I would like to understand why the media keeps reporting that he is low with that statistic.)