Because you have "Quick Reply" turned on, clicking on the "Reply" button will take the user to the "Quick Reply" section of the page. From there, they can either enter and submit their comment, or click on the "Use Full Editor" button.
You can disable "Quick Reply" so your users will always be taken directly to the "Full Editor" page.
Control Panel » General Display Settings > Post/Reply Page Settings category
Uncheck "Enable Quick Reply"