subdomain – How to make my sub-domain forwarding survive links?

I have my sub-domain blog.mysite.com forwarding to mysite.blogspot.com. I have installed the site-wide navbar on the blog. When visiting the blog through the sub-domain, when clicking on the mysite/forum (FluxxBB) link in the navbar, an error message is displayed “mysite.com refused to connect.” This forum link otherwise works when clicked from anywhere else, including directly from mysite.blogspot.com. Just not from blog.mysite.com.

I’ve tried looking at the admin settings of the Forum, and the Cpanel/godaddy admin for the sub-domain, but I can’t identify the source of this problem.