Lack of "Bookmark" function in pane buttons

[virginiayu]

As the screenshot shown below, there are only five panes in all without "bookmark". How could I add a bookmark funtion on Reader DC, the latest edition?

[Test Screen Name · Accepted solution]

If there are no bookmarks in the PDF you have opened, then there is no reason for Acrobat Reader to show a bookmark pane. So it saves useless clicks by removing it. Acrobat (paid for) always shows the bookmark icon because you can add bookmarks too. Acrobat Reader cannot add bookmarks.

[dahl431]

If I understand the answer above - if I dont see the bookmark symbol it is not able to add it anymore? I have the same PDF document but before (upgrade) I did see it. Why not now? 

[Test Screen Name]

Not exactly. 
1. Acrobat Reader cannot add bookmarks

2. This file has no bookmarks.