ms office - Built-In Add-Ins tab not displaying on the Ribbon of MS WORD 2010/2013 -

as following image word 2013 shows add-ins tab missing ribbon of document though "file-->options-->customize ribbon tabs" shows tab should display. same true other tabs shown in list of main tabs on left side of image. question: how can display these missing tabs?

the add-ins tab not have commands on it. why not appear in "choose commands from" list. unless add commands not show in ribbon though have checked box next in right hand column.

other tabs in "choose commands from" list, such smartart tools, context tabs , appear when in context. smartart tools appears if have smartart object selected, chart tools appears when chart selected, table tools appears when table selected, etc.

context tabs appear in right column when change drop-down either tabs or tool tabs.

some of tabs listed under main tabs context tabs, e.g. blog post , insert (blog post) appear when create blog post, outlining appears when document in outline view.