Q & A plugin - Permission Denied Error

Hello All. First time poster, long time Wordpress user.

Surprised I don't see any messages about the Q & A plugin here. Maybe I'm the only one trying to use it?

Trying to get the Q & A plugin to work with mixed results. I've gotta say that the documentation seems incomplete to me and also could use some clarification. Prepare to be bombarded with questions about this plugin.

We would like to have it installed on the main blog of our multi-site setup. We're using the bp-community theme. Following the installation instructions we try to go to .../questions/ask/ to fill in our first question (Why do we need to do this when there is a Question interface in the backend?). We get this error:

Permission Denied

Not Found / No Access
The page you are looking for either does not exist, or you do not have the permissions to access it.

Tried it on one of our sub-sites and it works (except for the page content and formatting [more on that later] but at least we don't get the error).

Why are we getting this error on our main blog site and how can we fix it?