I can't activate

I can't activate the plugin because I keep getting an Error 500. I occasionally gto this before which is why I wanted to use this plugin but I can't.
I have upgraded to php 7, my server error log is clear and I have deactivated jetpack which drastically reduced the error 500s

OK I activated it but now I cant access inframe.patbell.co.uk/wp-admin unless I deactivate it again, I just get a blank screen. I believe this might be to do with the theme (photocrati pro) which had a php 7 problem but fixed it and they had since I was in its wp-admin just beforehand.