Puzzle #54840: better solution exits

The puzzle seen here: http://en.lichess.org/training/54840

Analysis board: http://en.lichess.org/analysis/rr2k3/1Qp1qppp/1np1p1b1/P3P3/4P3/7P/1P3PP1/R1BR2K1_w_-_-_5_23?color=white#44

After : 1. axb6 Qd7

the tactics trainer expects: 2. Rxa8
after playing 2. Rxa8, stockfish rates the position as +9.2 at depth 18

The puzzle rejects my solution: 2. bxc7, yet after playing 2. bxc7, stockfish rates the position as +15.6 at depth 18

At the end of the 6 move sequence in the expected line (with 2. Rxa8), stockfish rates the position as +9.8 at depth 18

At the end of the 7 move sequence in the rejected line (with 2. bxc7), stockfish rates the position as +41.1 at depth 18

The puzzle should instead accept 2. bxc7 as a valid answer, but it currently does not.

Yes, it looks like bxc 7 is a better move. I experience the same thing with some puzzles and then i confirm with the analysis

How can you be 2500 in tactics and 1764 in classical?
I am 1200 in tactics.

I was 1900 tactics then I got mad and tactics trainer did not like me anymore. I mean I just went on full tilt lol.

I've only been playing chess regularly for 6 months, so I'm not so good yet, but I do tactics for hours every day.

When you do a puzzles how long does it usually take you? (On the hard setting) I usually spend about between 10 to 20 minutes on a puzzle, and even up to 45 minutes on the hardest ones.

Do you usually calculate the entire winning sequence or do you play what feels like the best move and go from there?
I think peoples might doing the puzzles anywhere between those two extremes, that might account for the differences in rating.

I try and calculate unless I am not feeling it. If im not feeling it I play then think.

I don't calculate for more than 5 mins (the 1200- 1500 puzzles), because in a classical match i don't have so much time. After 5 mins i play what i feel is the best move.

On the hard setting i can't solve them, not even after thinking for hours. I'm not smart enough to be good at tactics

I try to play within 10 seconds to train my bullet/blitz skills. which is one of the reasons that I stay around 1500 puzzle rating. Maybe one day when I've got more patience I'll try to calculate.

#6 its not so much about intelligence...
Let us say that tactics are 50% practice
20% intuition
20% positional understanding
6% talent
3% intelligence
1% luck :)

Luck should be part of and grouped with intuition.

First a disclaimer, when I check out these problems, I use a browser where I'm not registered in the cookies, so that I don't gain points from a correct solution.

As far as the accepted solution, with 2.Rxa8, the puzzle ends one move too soon, after the moves QxQ KxQ. There is one more critical move that needs to be made by White to secure the advantage. Yes, it seems obvious, but we all know that in chess, sometimes obvious isn't so obvious.