@ Nikola M: It's because Mozilla website only host 32-bit versions of those plugins. For Lightning, you have to use this build: http://releases.mozilla.org/pub/mozilla.org/calendar/lightning/releases/1.0b1/contrib/linux-x86_64/lightning.xpi
@ Nikola M: It's because Mozilla website only host 32-bit versions of those plugins. For Lightning, you have to use this build: http:// releases. mozilla. org/pub/ mozilla. org/calendar/ lightning/ releases/ 1.0b1/contrib/ linux-x86_ 64/lightning. xpi