As I see, Your site is not cached by Google at all (type cache:www.minibb.com or any other URL to see either it's cached). As Tom mentioned, it could take months until Google finds your page and start to index it.
miniBB is not helping Google to find and index the page, and basically there is no software which could do that. It just contains the code which could be indexed faster and proper than other software's codes, so it is "Google-friendly". It depends only on you as the site owner how successful your promotion campaign will be relatively to Google or any other kind of search engine. There are a lot of tricks regarding this, and miniBB is not a tool, it's a content holder.