developer option

Hi all, I was enable developer option, after that I accessed it at bottom of setting, but I can not turn on option inside that, because it is gray, Please help me to handle this issue, Thanks

I can't activate the developer option. I've tried hitting android version 7-10 times...the clicks register but nothing happens. I've wiped data, cache and Davlik and even system, used TWRP sideload to install lineage-14.1-20170619-nightly-clark-signed.zip along with...