Newbie issue

Not sure if this is the appropriate forum so please correct. I am working through section 6 of Getting Started with Rails ( and am getting the following error from the heroku logs :

2013-10-30T22:32:15.279058+00:00 app[web.1]: ActionView::Template::Error (PG::U
definedTable: ERROR: relation “comments” does not exist

I have tried running rake db:migrate again but to no avail. Any help appreciated and thanks in advance.