New to sceen need help with copy and paste key bind

I'm having trouble with screen binding keys, here's the .screenrc file.

ingnorecase on
markkeys ^[=^k:^]=^y
startup_message off

I wanted to bind ^k and ^y the readline kill and yank or cut and paste keys to the cut and paste functionality of screen but screen asks if I want to kill the current window when I hit ^a (for screen command) and ^k (for kill.) Also, am I under the correct understanding when I say that to set the mark for the beginning of the text to kill I have to hit "space" and then when I reach the end of the text to kill I hit "space" again?

Thanks