To allow the comment in pages, when you create a new page > scroll down to the Discussion section(If you can’t see this section, please click on the screen options button on the top right corner then check on the Discussion: http://i.imgur.com/g8v9Gtx.png) > check the Allow comments
The comment block is not showing on that page because it is using a BLANK template which has no comments since it’s a blank template. Only default template and the “layout” template support comments.