I go this when I tried to add the first external blog.
What the heck does it mean & what's the SOLUTION?
Warning: array_keys() [function.array-keys]: The first argument should be an array in /home/clickthr/public_html/click3media/wp-content/plugins/manage-multiple-blogs/manage-multiple-blogs-admin.php on line 240
Oopsy Dooopsy!!!! Some how we figured out you do not have write permissoins to the blog you are trying to add. You cannot do anything on the external blog so we do not see any point in adding the external blog to this blog as our limitations (Pssst: WordPress limitations led us to this) permit us from doing so. You can check with the site owner for the permissions to be able to write to their blog before we can add it here