Can't install the build pack

Trying to install the build pack on existing app, get the following error:

 -----> Fetching set buildpack https://github.com/leafo/heroku-buildpack-lua.git... done  !     Push rejected, failed to detect set buildpack https://github.com/leafo/heroku-buildpack-lua.git More info: https://devcenter.heroku.com/articles/buildpacks#detection-failure

I have cleared the cache no dice.
