According to Fox Sports:
(edit) Here's the link for the story

Chiefs RB Johnson to Cowboys?

The speculation about a trade that would ship Larry Johnson to Dallas is like that. It's all rumors; I've dug around Valley Ranch, trying to confirm that there have been substantive discussions with Kansas City regarding the disgruntled superstar running back, and all I got from it is an empty shovel, an empty notepad and a sore back. Except for one sliver. One grain. "The (Dallas) running backs don't offer that 'wow' factor,'' says a source close to the innerworkings of the Cowboys. "There isn't that guy who, when he gets his hands on the ball, makes everybody stand up and take notice.'' -- Scout.com