Why IF statement become false , If I write a name present in the nested list

When I input "Ali" it jumps to new user statement. Anyone please explain me why?

Data_base = [["Ali","1234","5000"],["Sara","1234","2000"]]
User_name = input("Enter your name")
if User_name in Data_base:
  print("User persent")
elif User_name not in Data_base:
  print("New User")
  New_User_name = input("Your name: ")
  Data_base.append(New_User_name)
  print(Data_base)