Git difftool not launching external DiffMerge program

DiffMerge

Not sure if this well help, but this is my configuration for difftool with DiffMerge. Note that I'm using msysgit Bash (not sure if it will be different for Cygwin or PoshGit users):

[diff]
    tool = dm
[difftool "dm"]
    cmd = C:/Program\\ Files/SourceGear/Common/DiffMerge/sgdm.exe \"$LOCAL\" \"$REMOTE\"

I'm currently using Git 2.0, but I seem to recall having set this up with either Git 1.8.x or maybe even as early as Git 1.7.x, so try it out and see if it works.

Bonus with Beyond Compare 3 Pro

I actually do most of my diffing on Windows nowadays with Beyond Compare 3 Pro, though sometimes I will still use DiffMerge. Here are all of my difftool settings if you want to make the switch:

[merge]
    tool = bc3
[diff]
    tool = bc3
[difftool "dm"]
    cmd = C:/Program\\ Files/SourceGear/Common/DiffMerge/sgdm.exe \"$LOCAL\" \"$REMOTE\"
[difftool "bc3"]
    cmd = "\"c:/program files (x86)/beyond compare 3/bcomp.exe\" \"$LOCAL\" \"$REMOTE\""
[mergetool "bc3"]
    cmd = "\"c:/program files (x86)/beyond compare 3/bcomp.exe\" \"$LOCAL\" \"$REMOTE\" \"$BASE\" \"$MERGED\""

I know this is an old question and I recognize that my situation may just be me being dumb, but I did spin my wheels trying to figure this out. Hopefully though, someone who made the same mistake as me won't be completely lost in future.

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Make sure items show with git diff!

I had a very simple one line change. Did a git add . and then got interrupted. Came back to finish up and decided to double check the diffs. I did not realize that doing a git add would stop me from being able to use git difftool.

Doing a git reset allowed git difftool to work.