not copying/yanking

Hi, I am using kubuntu with X11 server.
when I use this app and try to copy cell/row/all it doesnt copy anything to my clipboard. it seems doing something but for sure not copying anything. should I set something? 
I think in general xclip is used to copy anything to my clipboard (at least other apps are able to do that)

That is one of the things I missed the most in this app