Members Levels setting

Hi,

I am having a problem. I have created 4 levels. When I edit levels, i cant seem to drag "Groups" and "Blog" into either the Positive nor Negative Rules.

Does it have something to do with the fact that I have yet to activate my BuddyPress and that I have no Groups nor Blogs at the moment.

Then there is also the Problem that Strangers are not able to see all my posts on the homepage even though I have given them permission to view it on Edit Levels.

Is it due to the reason in my first point?

Will appreciate any help!
Thanks so much!
Regards
Jiahui