Opening LibreOffice Portable from application data files

This may sound stupid,but I just loaded LibreOffice Portable and found I couldn't open any of the data files created by an earlier version Of LibreOffice 3.6.3 by clicking on the on the files themselves. I can only open them by opening the correct LibreOffice application by opening the application that created it and then then opening the file that has the data.

I have loaded everything on a thumbdrive applications and data files.

I'm using Windows XP SP3. What am I missing?

Bruce