Membership and WPMUDEV updates plugin problem

Hi, I installed fresh wordpress multisite(Network) in http://assmpi.org/ . But I am having problem with "Membership" and "WPMUDEV updates" plugins. If I install Membership plugin then I can not enter in network admin. It shows 404 error. I tried with with all possible ways which I know.
Now please help me out from this problem.

Thanks
Brocas