Maybe since version 14 and certainly 15.0.1, I find Firefox browser will not download from Jazz on Line, http://www.jazz-on-line.com/index.htm.
In order to use Firefox an Internet Explorer rendering addon has to be used, the one I used is Fire IE,

https://addons.mozilla.org/en-us/firefox/addon/fire-ie/

A previous IE addon stopped working with the latest Firefox version.