Runway blog comments not saving

All,

I've installed v4.6.1 with the Business Starter Kit and included in the starter kit is the new Runway.Blog package.

When I create new post and attempt to add a comment, the form hangs at "Your comment is being submitted, please wait". In following the underlying javascript, the page is attempting an ajax post to /base/RunwayBlog/CreateComment/1075.aspx. Navigating directly to this page returns an error "Extension not found or permission denied"

I've done some searching through the forum and found this post which relates to the exact error, but is using the Blog4Umbraco package. I've checked the restExtensions.config file, and it appears to have the correct setting:

<ext assembly="Runway.Blog" type="Runway.Blog.Library.Base" alias="umbBlog">
    <permission method="CreateComment" returnXml="false" allowAll="true" />
    <permission method="GetGravatarImage" returnXml="false" allowAll="true" />
  </ext>

Does anyone have an idea of how to resolve this permission issue? I'd like to continue using the Runway package as I've already reconfigured the templates and doctypes, but not sure how to resolve this comment problem.

Thanks,

Andy