git submodule update --init Error while installing dot-emacs files

git submodule update --init Error while installing dot-emacs files

I try to install a dotfiles config for emacs
(https://github.com/dhaley/dot-emacs). I did all like instructed (download
and install of the macport of emacs via brew, clone of the repsitory) and
now when I use the command git submodules update --init I get the
following error:
$git submodule update --init
fatal: reference is not a tree: a2bcba9a92873900055dcaff640e4d31a650947e
fatal: reference is not a tree: 05f9cebc64842efa2968d49adb08330d15c7ffe8
fatal: reference is not a tree: 89611c7a6947787bf2f591e64e22b7444ea5ed41
Unable to checkout 'a2bcba9a92873900055dcaff640e4d31a650947e' in submodule
path 'override/bbdb'
Unable to checkout '05f9cebc64842efa2968d49adb08330d15c7ffe8' in submodule
path 'site-lisp/auctex'
Unable to checkout '89611c7a6947787bf2f591e64e22b7444ea5ed41' in submodule
path 'site-lisp/drupal-mode'
Some of these did not have an entry in the .gitmodules file and I added it
manually. But now I have no clue how to fix this error. I new to emacs and
the hole dotfile thing so if you can give me a hint it would be great (on
stackoverflow I found Git submodule head 'reference is not a tree' error
but did not really understand if this is my problem and how to fix it)
PS: I send a mail to Damon Haley the maintainer of the repository with a
link to this, as I found no forum to discuss issues on the github
repository.
Best Regards and thanks to everybody contribution to this greate community,
Dennis