I wouldn't call it a problem/error/bug/you can call it how you want, I'll call it a moment of idiotic lack of attention?
I struggled with a very common problem (it seems to be a common after some googling): "My Global.asax events are not being constructed/called - what should I do?"; this one was so familiar and I was sure that I've done everything like it has to be, so again what was it?
Finally I figured out my problem myself and was supprised of it (I'm seriously not jocking), the Global.asax file was not placed under the root folder of my web application (my web aplication structure is quite 'complex' because it suppose to serve many web sites that sits also in the same solution). I replaced it in the right folder (the one that the IIS is pointed to) and that's it.
I think that post can solve to (starter?) web developers this (common?) problem while it occurs, because google's results didn't supply very good solutions for this one.
What aobut me? Even after developing and designing many web applications, things like that could happen to anyone 