PluginAdMob doesn't work

i’ve completed the installation of the SDKBox Admob plugin, and… nothing works. I’ve done everything I can, and nothing works. For the thousandth time, I’ve followed a tutorial, or guide step by step, and something goes wrong, and no one knows why. In this case I’ve followed the Admob with cocos2d guide, but when I try to include "PluginAdMob/PluginAdMob.h>, it apparently doesn’t exist. For some reason. It simply does not exist. I mean, I never expected it to exist, because something has to go wrong, at every step, and most importantly, for no reason, but after three days of tirelessly searching, I expected to at least find a clue. No. No one else has this problem. What am I doing wrong? Is it because I’m using Visual Studio or what?

Oh, you are using Visual Studio for building Android project ?

yes, I am.