Giang,
The 3.1.2 release doesn't have a "Load Bootstrap" option anymore. The newest release just has a "Load jQuery" setting which will load a compatibility mode version of both jQuery and Bootstrap that should make things work better. Also, since you're using JFBConnect, the Load jQuery setting should be used in that extension as the SCLogin module's "Include jQuery" setting is ignored when JFBConnect is installed.
I hope that helps get you going,
Alex