"Twitter user name" input is missing

1. Enable views_ui and twitter modules.
2. As the admin user, go to "My account" > Edit > Twitter accounts.
3. At "Twitter user name", type the Twitter user which you want its tweets to be listed (ie: drupal). Hit "Add account" and you should see that the account gets listed and the account image and description are visible.

There's no "Twitter user name". I've been using this module for months and I always could seen that input. But now in my new site is missing and I can't add my twitter account. Here talk about this problem and its solution, but I enabled all submodules and and there was no change.