he or her must accept chalenge
Can't challenge friends in live chess

Leon
Have you asked your friend if they have turned off their challenges? Or if they have their min/max ratings set to something outside of your own ?

Is there some trick to solve it?
The same thing bothers me - I want to play live chess with a friend, see him in Live chess interface (http://live.chess.com/live?v=2015102301), but when I challenge him (or he challenges me), nothing happens.
Once it worked well for us, but don't know why. We've checked the live chess settings, tried different browsers, tried to restart computers, I'd even tried to challenge him from Android app.
But there is still nothing :(

Smichal,I also don't know how all these things work,by the way,I've got this problem 5 years ago.Kohai from the chess.com staff wrote to me:"Have you asked your friend if they have turned off their challenges? Or if they have their min/max ratings set to something outside of your own? ".

Yeah, I know it was 5 years ago, but there was no other mention of this problem on chess.com so I tried to ask anyway.
And yes, we already checked the settings of live chess, everything is set up correctly (accept challenges from everyone, no rating limitations).
Thanks anyway.

SOLVED:
My friend had me blocked. He doesn't know how it happened, but I was blocked not in a Live Chess settings, but in general settings at http://www.chess.com/home/privacy .

Challenge failed. Your challenge does not match the member's current match settings
What to do؟؟؟
You'll probably have to challenge someone else or put out a random challenge. One of the settings of the player you are trying to challenge is preventing it and could be something you can't change to make it work.
Can anybody help me? When I go to live chess to play with a friend (he/she is online) I click the play button but nothing happens.However,I can watch his/hers game.Thanks in advance.