User not showing on list, but I can't add it.User already exist !!!

User not showing on list, but I can't add it.User already exist !!!

Dear Support Forum ,

I have facing an issue for adding an user email address . but when i try to add this then it's showing "User already exist."


Please Solve this issue . i went to create this user sharif@avatia.net  but when i try to create then it's User already exist


Please Help Me

Thank You