Launc in new window not working

I reported that "launch in a new window" was not working some time ago and to be honest the reply was slightly over my head so I have accepted the published presentation in the meantime. However my students are now asking for a bigger window so I have returned to the problem. I did a short test presentation today to check that my LMS (JoomlaLMS) was accepting "launch in a new window" and it worked fine. However the presentation I an trying to change to get it to launch in a new window totally refuses to do so. I have republished it several times and even created a new template to publish it to but it still refuses to behave! The interesting thing that I have noticed is that there is no "launcher" file in the file list even when I have ticked the launch in new window box. This is the only difference I can see in the test presentation which works fine and the presentation that refuses to behave. Can anyone explain this or even better - help!