EndNote Web in Firefox problem


I’m new to using EndNote Web, and am trying to export citations from Science Direct.  I have a read a few guides online on how to do this, but it doesn’t work in Firefox for me.  If I click ‘export citation’, choose the radio button for RIS format and click ‘export’ a download box pops up stating ‘you have chosen to open the file …’ instead of a dialog box asking if I want to save the citation to EndNote Web.

Any suggestions?