Xposed cannot install?

Hi I Found a Problem that I cant install xposed and they said like this :

Copying Xposed-Disabler-Recovery.zip....
Mounting / System Writeable
Mount: Permission Denied (are you root?)
could not mount / system writeable
trying to continue anyway...
cp: can't cretate'/system/bin/app_process.orig':read-only sfile system

failed to create a backup of /system/bin/app_process

I have Sony Experia E3, Kitkat version, and... rooted use kingo.
have anyone have the same problem like this?
Thank you :)