Firstly sorry, my english are not so good !
I bought a USB OTG cable and I tried to connect various devices (memory flash, mouse) ; unsuccessful.
Option appears in my settings (see attached screenshot)
I checked the USB connector and it looks like my phone does not generate 5 volts. I made a USB OTG Y cable with external power supply and no results.
I rooted my phone , I used USB OTG Helper, to no end.