Inabality to Attack

This is my second post about Attack in chess. Many players succeed in opening but then they stuck and can not continue, because they are not able to Attack, they simply dont know how to do this.

I was playing with black peaces:

So this is clear example how one can lose game after having big advantage in the opening. After move 14. dx5 he had big advantage but he could not use it, he dont knows how to push oponent to make mistakes.

Diagnosis: Inability to Attack