Not able to merge in changes app.

When I use Changes to view a diff the merge options are always grayed out.

*SIMPLE STEPS*

Steps to reproduce:
1.) Open a new text file.
2.) type "foo"
3.) save file as foo.txt
4.) in the same file hit return type "bar"
5.) save the file as foobar.txt
6.) compare the two files in changes
7.) go to top toolbar > merge
8.) all merge options are grayed out

Expected result:
if I open a file with changes I expect to be able to intelligently merge changes from one file to another changed file.

Actual result:
I am never able to merge in the program changes.app under any circumstance I have tested.

Test scenarios I have run:

Trying to merge changes between SVN revisions.
Trying to merge changes between SVN conflict files.
Trying to merge changes between text files.

I bought Changes to be my merge editor for source control. The main use case I need it for merging source control conflicts. I am dissatisfied with my purchase. I had high hopes for this program since there is nothing out there that does this very well.