in 3 seconds just why?
If you tell us the tactic number and the move you suggested, we might be able to help you figure it out.
What do they say in the comments about your move? On many tactics, somebody will have suggested alternate moves in the comments and people are usually helpful in pointing out what is wrong with those suggestions.
Occasionally, people find a legitimate error and report it to the staff.
But without knowing the tactic number and your move, we can't say.


in 3 seconds just why?