Membership Any other Language Not working

Hi

im facing a problem with Changing Membership Language

Im using Buddypress and im runing my website with arabic Language ,

i tryed to make a copy of membership language file and translate it , but it didnt work out only shows English Language , i tryed to put it in Language folder , Membership Language folder , Theme Language folder ,

but all didnt work out ,

so can you tell me please how can i make it work 100%

thank u again for ur great assist & help