Google substruct + copying plugin_assets from vendor to public

Hi,

I am attempting to install Google substruct - a ruby on rails
application.

I get to the last step in install - ruby script/server

The launch gets hung up here:

Attempting to copy plugin assets from ‘/home/lynn/substruct_rel_1-0-a2/
vendor/plugins/substruct/assets’ to '/home/lynn/substruct_rel_1-0-a2/
public/plugin_assets

Any ideas much appreciated.
Lynn