"Invalid Username or Password"-error on WPMU DEV-login via the dashboard plugin

Hey guys,

Each time I try to login to WPMU DEV via the dashboard plugin I get an "Invalid Username or Password"-error. The login-information works - apparently - to login to your regular site, so that shouldn't be the problem. The error occurs in Firefox and Chrome, and after cleaning the cache. Please let me know what else I can do to fix the problem.

Thanks.
Manuel