SetLocaleInfoW always get 1004 flag error

I want to set locale language to English, but I always get 1004 flag error when using the API.
Please help me.. I got stuck in the problem for a long time 😥

  LCID lcid = 0x409; //English - United States
  if (SetLocaleInfoW(lcid, LOCALE_SNAME, _T("en-US"))) 
      printf("Locale changed!\n");
  else
      wprintf(L"Error %d \n", GetLastError());