I have installed this add-on (version 1.4.0 and also 1.3.1) on a standalone JIRA server version 6.2.5.
I can add the gadget to a dashboard and fill in the various options. Clicking on save however lets me see a percentage bar for a few seconds then it reverts back to the 'Edit screen'. Viewing this in another browser shows an empty gadget.
Any idea what the problem can be?