Missing Merge option

I am sorry to trouble you with this, but I do not see a Merge option on the
Advanced Get dialog. I've read the documentation that shipped with the
product, the online documentation, and even this article
(http://www.pushok.com//tickets_addmodify.php?id=1973), but still don't see
it. The closest option is 'Revert changes in', but that doesn't perform a
merge (unless I'm not doing it right, but I followed the instructions in
documentation under 'How to merge branches').

Am I missing something?

Attached is a screen shot of my Advanced Get screen.