Condition -> User has role -> Drop down missing

I've installed all modules which come with workflow_ng. Then I've created a new rule configuration. As condition I've selected "User has role(s)". On the next page I'm used to select one or more roles but I had no chance to do it. The drop down is missing. I've also tested it with dev version. Same problem. Now I've switched back to 1.6. There the drop down is available.