ROOT TWRP and rom 5.1 Archidroid

Hello,

I recently installed Archidroid 5.1 but I do not have access to the root whereas before I had the root on cyanogen rom and it's worked well.

I currently TWRP and i have root checker, when I checked if the root is installed he said: "Root access is not Properly installed on this device"

Someone already had this kind of problem?

Sorry for my bad english, i'm french

thank you in advance