Have you purchased the Creative Cloud membership or using the Trial version of Premiere pro ?
If you navigate to the web link :- http://www.adobe.com/cfusion/tdrc/index.cfm?product=premiere_pro&loc=e n_us
It states :-
Trial limitations
Adobe Encore® CS6 is not available as a trial. Encore CS6 will be installed as part of the trial for Adobe Premiere Pro CS6, Creative Suite® 6 Production Premium, and Creative Suite 6 Master Collection but will not be available for use until you purchase.
{moving the discussion to Adobe Encore forums}
