Sounds like you dry fired it to me. Maybe in you "taking a few steps forward" and all that(what's up with that anyway???)
I told you whats up with that and its not that big of a deal it was a mistake. This board is good at helping people so dont turn this into like most other boards when one guy starts critisizing and all the sheep follow.
you nocked the arrow off the string. When you released it caught hold or something on a fletching. Who knows, but it sure sounds like a dry fire to me.
The arrow did not come un-nocked. The hole in the side of my friends house and the shattered arrow are proof of that. I believe if it would have just caught the fletching it would have ripping the fletching and not sent the arrow at enough speed to penetrate wood.