Okay I looked up some stuff about weight painting, i didn't really get it. But after tinkering around with it i managed to get this result.
Click spoiler to show a picture of the problem
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(http://i.imgur.com/JgVMKPx.jpg)
I fixed the legs and crotch, but the torso along with small parts of neck and the arms is invisible.
And thank you all so much for your help! I really look forward to understanding how to make characters for EF-12! :)