What I meant is need detailed info about your server public root, WordPress root and Q2A root.
Example:
your server root path is
Public Root:
/var/public_html/
WordPress is on Public root
/var/public_html/wp-load.php
Q2A in sub-directory on WP
/var/public_html/qa/qa-config.php
So as above you can see WordPress lies on the server root (public) and Q2A lies under WordPress root.
If your WP and Q2A setup is in that way than there is a possible issue with WordPress or Q2A .htaccess issue. In fact it seems like rewrite mod issue.
Please post your WordPress and Q2A both .htaccess code here also update your exact path for wp-loader.php and qa-config.php
Or just try adding below in WP .htaccess file. Somewhere after RewriteBase /
RewriteRule ^index\.php$ - [L]
BTW:
I just noticed, you have set absolute WordPress path in QA config. Try adding relative first and if it doesn't work than try to add rewrite rule mentioned in above line.