Problem using the WPMU DEV dashboard plugin

I signed up to your site using my facebook account. I wish to use the Dashboard WPMU DEV plugin and then I have to get my API Key. Inorder to get that I have to Login to WPMU DEV. When I enter my email adress(as on my profile on your site),password and then login it responds saying “Invalid Username or Password. Please try again.”.

How do I change this? I mean How do I login to my Dashboard plugin using my facebook account?