Hanging cabinets

Edit
jennalauritsen2

Handyman questions

My boyfriend and I tried to hang cabinets in our kitchen, but we are kind of failing. Some of them went in fine, but on this one, the things that hold the screws into the wall (those plastic things- not sure what they're called) just keep coming out.  Here's some pics. What are we doing wrong? and what should we do? Help!
Img 0205
Img 0205 Img 0206