Unions let Edwards down

How can Obama and Hillary get 30% of the union vote and Edwards get only 24%. Really? Here is the only candidate of the three that says I am unquestionably on your side, and he gets the least support.
AFL-CIO result

Obama and Clinton clearly said they supported the Peru Trade Agreement not 1 month before this caucus. Edwards condemned it as a NAFTA extension and you give your votes to the two that want to screw you even harder than you already have been.
Labor wants answers
Ooops - maybe we can just sit this one out!
Help me understand the logic and reasoning that goes with that kind of thinking. Edwards has fought corporations as a trial lawyer and then as a Senator, basically his entire adult life, and you turn your back on him. Hillary was a corporate attorney, she was a Republican in college and she really doesn't have a problem with the NAFTA agreement her husband passed. What 30% of the union membership would vote for her over Edwards. Are you kidding me!
I think unions are critical to employment issues in this country and I give them all the credit for creating the middle class in this country. But some in this generation of union leadership are baffling. I think that the leadership in some of these unions is more concerned with there own political clout than they are with issues important to their younger members.