Missed winning combination

from now on I'll post some crucial match of mine in witch something notable happend. I'll do that mostly for my convenience, as a way to study and remember my own mistakes, or my good movies and strategies.

This very first time is about a missed key move that would have given me a clearly better position than the one I did in the real game.

Here is the match and the key moves commented by me are 10 and 11: