You took too much time. There are two main parts time taken and the correct moves. If you take significantly longer than the average solve time and get all the moves correct, you get at least one point.
https://support.chess.com/customer/en/portal/articles/1444811-how-does-the-time-and-ratings-work-
Thanks but it doesn't explain the fact that when I solve it fast & wrong it still gives me -9 although I didn't take much time to make the move.
And when I make the second move wrong it still gives me a minus as if I failed totally.
Your main focus and goal is to understand the tactics youre trying to solve. If the rating is your main concern, or goal, youre not going to improve as fast. Who cares if you take a long time to solve a tactic and only get 1 point? the goal is to understand the tactic. As far as losing 9 points? Again...who cares. You goal is to increase your knowledge, not worry about a number.
Your chess will improve when you realize rating points are largely irrelevant. It's a tool for matching players of roughly equal skill, that's all. Least of all does anyone care about your training ratings.
Thanks for your wise comments. Loss is a main part of the game & it is what makes it exciting, but "Unfair Loss" is what irritates me & makes me lose concentration out of nervousness. I reached 1500 a couple of days ago & now I'm 1453 because of less than ten mistakes ( I solved the last few puzzles with the attitude of "OK whatever it is"). It is like working for a company that gives you 1 $ per day and fine you with 10 $ for whatever mistake you do, surely this makes you a kind of despearte doesn't it?
Thanks for your wise comments. Loss is a main part of the game & it is what makes it exciting, but "Unfair Loss" is what irritates me & makes me lose concentration out of nervousness. I reached 1500 a couple of days ago & now I'm 1453 because of less than ten mistakes. It is like working for a company that gives you 1 $ per day and fine you with 10 $ for whatever mistake you do, surely this makes you a kind of despearte doesn't it?
Actually no. Chess is a game with mistakes just waiting to be made. Everyone makes mistakes. All you can do is try and limit the mistakes as much as possible. If losing is causing you to lose concentration, that is something you are going to have to deal with.
When you make mistake, accept the fact that its done. You cant go back and undo it. Learn from it.
I understand this Sir. What irritates me and makes me lose concentration isn't my mistake but what happens as a consequence of it. "Eye for an Eye" is fair enough but "Life for an eye" is an exaggeration isn't it?
And I know that it's just training but I want to know how the points are calculated so I can know whether my idea of "unfair" is right or wrong.
I understand this Sir. What irritates me and makes me lose concentration isn't my mistake but what happens as a consequence of it. "Eye for an Eye" is fair enough but "Life for an eye" is an exaggeration isn't it?
Chess is just a game, its not a matter of life and death. Enjoy the game and have fun! One of the great things about chess is you are going to have all kind of mistakes that you are going to be able to use to improve.
Thanks but it doesn't explain the fact that when I solve it fast & wrong it still gives me -9 although I didn't take much time to make the move.
If you solve it incorrectly then it doesn't matter how much time it took you. Some problems give partial credit, but in general, solving incorrectly will give you a rating loss.
Thanks for your comments 
Wish me luck and fun 
I'm glad I found this thread. I thought I was the only person feeling demoralized
If I may take the liberty to repost my comment from another thread with the same topic,
"At least, +1 or 2 is better than -10, so it pays both immediately and in the long run, to take the time you need to make the right move, rather than making a fast and incorrect move. But let's say one player takes quite a long time in the TT session, makes one wrong move, but makes all the correct moves and solve all the other puzzles apart from that. +4 - 10 is -6. A bit unfair, perhaps."
In the statistics, you can also see your amount and percentage of solved and failed problems, and which kind of problems you score better or worse in, so that you can try to improve at the kind(s) that you are less good at.
On the other hand, in the Lessons, it is almost impossible to lose instead of gaining rating points, even if you make several mistakes.
I'm glad I found this thread. I thought I was the only person feeling demoralized
Thanks for your comment I thought like you did too.
If I may take the liberty to repost my comment from another thread with the same topic,
"At least, +1 or 2 is better than -10, so it pays both immediately and in the long run, to take the time you need to make the right move, rather than making a fast and incorrect move. But let's say one player takes quite a long time in the TT session, makes one wrong move, but makes all the correct moves and solve all the other puzzles apart from that. +4 - 10 is -6. A bit unfair, perhaps."
In the statistics, you can also see your amount and percentage of solved and failed problems, and which kind of problems you score better or worse in, so that you can try to improve at the kind(s) that you are less good at.
On the other hand, in the Lessons, it is almost impossible to lose instead of gaining rating points, even if you make several mistakes.
Thanks for your comment. May be it helps some people but it irritates me quite much, not because one should solve the puzzles carelessly but because it's strange to take your time, solve it wrong and find yourself losing 9 points while on the other hand you can take your time, solve correctly and find yourself getting 1 point only. One can't be sure of his move being correct until he makes it & it is really unfair to do your best and then find yourself losing what you get by solving 9 puzzles.
I would like to add that I'm not underestimating the usefulness of Tactics Trainer. It's a great tool that helps me a lot. My only concern is with its way of evaluation.
Just for the record: Tactics Trainer has just given me 1 for every passed puzzle and -6 for missing the last move of a three moves one.
Hi all!
Honestly I don't understand why do I get +1 point when I solve a tactics puzzle here correctly and yet when I'm wrong I get -9 !! Could you please explain on what basis does this happen?