multisite error when save changes

Hi, great plugin and very useful.

In wp multisite I am unable to “Save Changes” in Settings->BuddyDrive and get this error page. I tried to change either the max upload size and Name for main subnav but both received the error page.

Please view screenshot http://postimg.org/image/j5qvo1e8x/

It works in wp single mode. Advise?

Thank you.

http://ww.wp.xz.cn/plugins/buddydrive/