On Tue, 19 Oct 2010 16:26:40 -0400, Kaminsky,Matthew <[log in to unmask]> wrote:

>We're running 15.5, ....  On the web interface for the site configuration, the text box at the top says "Find or Add Configuration Variable," but we've been unable to add new config variables there.

This part of the interface was made to work properly in LISTSERV 16.0.  Until you upgrade, the workaround is to add the dynamic query variables in site.cfg/go.user.  If you add them there (even in 'stub' format) you should then be able to edit them in the WWW interface.