libreoffice mozilla plugin not working

[yonnie]

Using LM13 mate 32-bit. When I go to a website that has a .xls sheet or .doc, my Firefox won't ask what to open the page with, instead it just displays a blank page. The libreoffice plugin is installed and not disabled. What could be causing the problem?

I go to two other machines, 1 running same version of LM, the page opens right up into Libreoffice. The other machine tested, uses another distro and it opens up Libreoffice just fine.